mocha hazelnut layer cake (milk bar-style)

Chocolate cake with a coffee soak, layers of hazelnut frosting, crunchy filling, and a stout ganache make this Mocha Hazelnut layer cake a real showstopper.

I’ve been itching to make one of Milk Bar’s spectacular, bare-sided triple-layer cakes ever since my sister and I dropped $75 at the opening weekend of Milk Bar’s L.A. store to try “a bit of everything.” If you haven’t seen a Milk Bar cake before, they’re towering cakes with bold layers of frosting and crunchy fillings visibly between equally thick, plush layers of cake. Christina Tosi, the brilliant mind behind Milk Bar’s spectacular creations is known for inventive desserts that are rich and decadent without being tooth-achingly sweet. They’re great.

The official Milk Bar All About Cake cookbook has been staring me down for months now so, when Jimmy requested a coffee hazelnut birthday cake, I finally had a good reason to crack it open. I was determined to deliver something unique. The wrinkle: Jimmy loves hazelnut but doesn’t like Nutella (weird, I know!) so I had to find a way to incorporate the hazelnut flavor without using a Nutella-based recipe. 

In the end, I used Milk Bar’s basic Chocolate Cake recipe, the Stout Ganache from the Pretzel Layer Cake, the Chocolate Hazelnut Frosting from the Banana-Chocolate-Hazelnut Cupcakes recipe, and adapted the crunchy filling from the German chocolate cupcakes to use hazelnuts instead of pecans. The coffee soak, to keep the cake layers moist, I basically made up on the fly. And thus, a Milk Bar-style mocha hazelnut layer cake was born.

but is a 3 layer mocha hazelnut Milk Bar-style layer cake practical?

Oh, absolutely not! There are five-and-a-half components that need to be created before you can even begin assembling this cake. If you’re looking for a practical cake, go for this ginger-pumpkin spiced pound cake or do a basic sheet pan cake with frosting.

To make this just slightly more practical, though, I’ve noted which two components are optional (the ganache and the hazelnut crunch). Bare minimum, all you need to make are the cake, the frosting, and the coffee soak.

pros and cons of a Milk Bar cake

What I really loved about the process of building a Milk Bar cake was that the assembly itself was so simple that my brain was free to focus more on creating the individual components without feeling frazzled or rushed. Yes, there are multiple components but because they can all be prepped ahead, or quickly created right before assembly, you don’t feel like you’re constantly fighting against a clock or trying to time everything perfectly or convince icing to stick on a warm cake.

I also appreciated how efficient Milk Bar recipes are. Where usually you’d bake 3 separate round cakes for a layer cake, the Milk Bar method has you bake one rectangular cake and use a 6″ cake-cutting ring to cut your layers out of it.

But, like I said, this is not the kind of cake you can — or should — make all in one day. Here’s how I did it:

• Friday: Make the hazelnut praline paste for the frosting
• Saturday: Make the frosting and the cake, refrigerate both
• Sunday: Make the hazelnut crunch, the chocolate ganache, and the coffee soak. Re-whip the frosting. Assemble the cake.

What I didn’t love about some of the recipes in the Milk Bar book is that they call for really specific, often expensive, hard-to-find ingredients like hazelnut praline paste and Feuilletine and don’t include recommendations for cheaper alternatives. I’ve noted below where I’ve made more affordable alterations to the recipes, but if you’d rather spend the money to just have the right thing without any extra steps, you do you.

making the chocolate cake

While you can probably use any 13×9″ chocolate cake recipe here, the official Milk Bar chocolate cake recipe produces a uniform cake with an exceptionally flat surface. Most cakes end up with a slightly domed top that needs to be sliced off for layering, but the Milk Bar recipe produces a flat-topped cake that requires zero trimming. Make sure that you really let your mixer run for as long as the recipe says between steps to get a beautifully airy cake batter.

If you use a different chocolate cake recipe or end up with a dramatically domed top to your cake, use a serrated knife to trim it flat. Use the scraps in the bottom layer. If your cake top is only slightly domed, it should be fine. These aren’t meant to be perfect-looking cakes, anyway. A little unevenness is okay.

TIP: Double-triple check the size of your sheet pan. In doing some research for this post I ran across several blog posts and forums that say the Milk Bar recipes are sometimes inconsistent with the size of sheet pan they call for. If your quarter sheet tray is smaller than 13×9″ or has low sides you risk the cake batter spilling over during baking. Put another sheet tray underneath it to catch any spillage.

Money Saving Alteration: The original recipe calls for a 1/2 cup of buttermilk, but since the frosting calls for 4 TBSP whole milk, I’ve adjusted the cake recipe below to use whole milk (mixed with lemon juice or vinegar) to replicate the chemical reaction of buttermilk without spending money on two kinds of milk.

the secret to true hazelnut chocolate frosting

This frosting, which I borrowed from All About Cake‘s Banana-Chocolate-Hazelnut cupcakes is the icing on the cake here, literally and figuratively. It’s buttery and light, and the hazelnut praline paste adds a rich, sweet texture that doesn’t make your teeth ache.

The only thing is… hazelnut praline paste is both expensive and hard to find. I couldn’t find it in any grocery store near me, and online it was going for almost $20 for 11 ounces, which meant that, even though I was doubling the batch, I’d have leftover praline paste, which I didn’t need. So… I made my own praline paste. Exactly the amount I needed, with none leftover. And honestly, if you have the right tools, I think you should do that too. It’s really not that hard.

What is hazelnut praline paste? It’s hazelnut praline (toasted hazelnuts coated in a hardened caramel) pulverized in a food processor until the nuts release their oils and it reaches a peanut butter-like consistency.

How to make hazelnut praline paste: First make, make hazelnut praline. Toast the hazelnuts and remove the skins, then heat granulated sugar and water in a non-stick skillet on the stove to make caramel. Pour the caramel over the toasted hazelnuts and let it harden and cool. Then, break the hazelnut praline into pieces and send them on a trip through the food processor until it turns into a peanut butter-like paste. Refrigerate until you’re ready to use it. Boom.

You will need: A food processor (I used my beloved 3.5 cup mini-KitchenAid food processor) and a silicone baking mat.

I know it seems complicated and potentially messy, but the caramel is actually really easy to clean up — once it hardens, it comes off the silicone mat without a problem, and if it gets anywhere you don’t want it, hot water will melt and dissolve it right off.

Time-Saving Tip: Just buy the pre-made stuff.

how to assemble a Milk Bar-style layer cake

Instead of baking individual cake rounds, Milk Bar cake rounds are cut out of a single 13×9″ rectangular cake. The bottom layer of cake is built out of cake scraps inside of the metal cake ring, which you line with the acetate cake collars to hold everything in place.

Start by cutting out your two 6″ cake rounds. Then, place the 6″ metal cake cutter in the center of one of the cardboard cake rounds and line it with a sheet of the acetate.

Order of mocha hazelnut layer cake assembly:

• Layer 1: Cake — Break the remaining cake into chunks, and press it into the bottom of the cake round. Don’t be shy here. The cake scraps don’t have to be pretty but they do have to support another three layers of cake and frosting. Press ’em in, tear the cake pieces into chunks, crumble them up, and really push them in firmly. Once the cake comes out of the cake ring and you remove the acetate sheets, that bottom layer still has to support the weight of a cake above it. You want a firm foundation!
• Layer 2: Coffee Soak — Use a spoon or a pastry brush to liberally douse the cake layer with 1/3 of your coffee soak. The coffee soak will help the scraps stick together and keep the cake moist.
• Layer 3: Chocolate Ganache (OPTIONAL) — Half of the ganache goes on here. It’s a pretty thin layer, spread it as evenly as you can across the surface of the cake.
• Layer 4: Pecan Crunch (OPTIONAL) — Half of the pecan crunch mixture goes down here — this one’s a bit harder to spread so try to scatter it evenly and then use the edge of your spatula to gently shift the mixture around on top of the ganache layer.
• Layer 5: Chocolate Hazelnut Frosting — 1/3 of the chocolate hazelnut frosting goes down next. If you made this a day or two in advance it will firm up in the fridge. Loosen it by putting it back in your mixer bowl and beating it at medium speed for 3-4 minutes.

Insert the second cake round (if one of the two cake rounds is messier than the other, use that one). Then, take the second acetate cake collar strip and insert it inside the first one, tucking it behind the second cake round to hold it in place.

Repeat the order above: Coffee soak, chocolate ganache, pecan crunch, and chocolate hazelnut frosting.

The final layer: Place your last cake round on top, with whichever side is smoothest facing up. Apply the rest of the coffee soak, and a final layer of chocolate hazelnut frosting.

And that’s it! You’re done.

The final step is to stick the whole mocha hazelnut layer cake in the freezer for 3-5 hours

This gives the cake a time to set — the coffee soak freezes, the cake layers get all cozy and meld together.

Before serving, take the cake out of the freezer and let it defrost for 2-3 hours. Before serving, slide the metal cake ring off and peel off the acetate. Start slicing!

To make a Milk Bar-style cake you will need:

• Acetate cake collars — The Milk Bar book calls for 3″ tall ones, but I bought 4″ ones and found they were just the right height. You’ll need two 20″ long strips.
• 6″ cake-cutting ring — You will use this to cut out your cake layers and also to assemble the base of your cake.
• 8″ cardboard cake rounds — You’ll need to refrigerate or freeze your cake when you’re finished, these are perfect for moving/picking up your finished cake and fitting it in your freezer or fridge.
• Small spatula — Since you need to be able to reach down into the acetate tube to spread your frosting and ganache layers, it helps to have a small, easily maneuverable tool on hand.

Mocha Hazelnut Milk Bar-Style Layer Cake

Recipe by The Practical KitchenDifficulty: Medium

Servings

8-12

servings

Prep time

1

hour 

30

minutes

Baking time

30

minutes

Assembly Time

30

minutes

Day 1: Make the hazelnut praline paste for the frosting
Day 2: Make the frosting and the cake, refrigerate both.
Day 3: Make the hazelnut crunch, the chocolate ganache, and the coffee soak. Re-whip the frosting. Assemble the cake.

The cake needs to freeze for at least 3-5 hours after assembly and defrost for 2-3 hours before slicing. Take it out 2-3 hours before serving to thaw.

Ingredients

• Basic Milk Bar chocolate cake

• 115g (8 TBSP) unsalted butter at room temp

• 225g (1 cup + 2 TBSP) sugar

• 60g (1/4 cup) brown sugar, tightly packed

• 3 large eggs

• 110g (1/2 cup) whole milk, mixed with 1/2 TBSP lemon juice or white vinegar, stirred and left to sit for 5 minutes*

• 105g (1/2 cup + 3 TBSP) neutral oil (grapeseed, canola, safflower, vegetable, etc)

• 5g (1 1/4 tsp) vanilla extract

• 154g (1 1/4 cups) cake flour

• 70g (1/2 cup) cocoa powder

• 6g (1 1/2 tsp) baking powder

• 7g (1 3/4 tsp) kosher salt

• Hazelnut Praline Paste (for the frosting)

• 4 ounces (1 cup) hazelnuts, toasted with skins removed

• 4 ounces (1/2 cup + 1 TBSP) granulated sugar

• 1 ounce (1/8 cup) water

• Chocolate Hazelnut Frosting

• 80g (3 oz) semi-sweet baker’s chocolate

• 220g (16 TBSP) unsalted butter, softened

• 320g (3 cups) powdered sugar

• 60g (1/2 cup) cocoa powder

• 1 tsp salt

• 60g (4 TBSP) whole milk

• 200g (1/2 cup + 2 TBSP) hazelnut praline paste

• Hazelnut crunch (OPTIONAL)

• 125g (1 cup) hazelnuts, toasted with skins removed

• 40g (3 TBSP+2 tsp) canola or vegetable oil (some sort of neutral oil)

• 20g (1 TBSP+1 tsp) brown sugar, packed

• 60g (3/4 cup) Frosted Flakes cereal, crushed (a cheaper alternative to feuilletine)

• Chocolate Stout Ganache (OPTIONAL)

• 70g (1/3 cup) chocolate stout

• 45g (3 TBSP) heavy cream

• 250g (9 ounces) 72% dark chocolate, melted

• Coffee soak

• 1/3 cup freshly brewed coffee

• 3 tsp sugar

Directions

• Hazelnut Praline Paste (Day 1)
• Toast your hazelnuts on an un-greased sheet pan in a 350F oven for 10-15 minutes. To remove the skins wrap them in a dishtowel and rub them around. It’s okay if some skins are still on, but try to get most off. Transfer the toasted, peeled hazelnuts to a sheet pan lined with a silicone mat.
• Meanwhile, combine sugar and water in a skillet over high heat. Swirl to combine. The sugar will begin to melt and bubble and after a few minutes will take on an amber color. Keep gently swirling so the sugar doesn’t burn. It’s up to you how dark you want the caramel to be. The darker it is, the deeper the caramel flavor will be. If you start to see wisps of smoke that’s a good sign that you should be done.
• Quickly and carefully pour the liquid sugar mixture over the hazelnuts on the silicone mat. If the mixture doesn’t coat all the hazelnuts, pick up the loose ones and place them on top of the liquid or try to roll them in it. The caramel will harden quickly, so work fast.
• Once the praline has cooled, peel it off the mat (it should come up easily!) and break it into pieces. Place the pieces in the bowl of a food processor and puree until a peanut butter-like texture forms. If you seem to be struggling to achieve the peanut butter texture, drizzle a teaspoon or two of canola or peanut oil into the food processor. This whole process might take anywhere from 3-5 minutes.
• Transfer to an airtight container and leave out at room temp until ready to use. (Praline paste can be stored in an airtight container at room temp for several months.)
• The Chocolate Cake (Day 2)
• Preheat your oven to 350F. Generously spray a quarter sheet pan (13×9″) and line it with parchment paper or a silicone mat.
• Combine the softened butter, brown sugar, and granulated sugar in your stand mixer bowl. Use the paddle attachment to cream the butter and sugars together on medium-high speed for 2-3 minutes (set a timer!) until light and fluffy. Scrape down the sides of the bowl about a minute-and-a-half in, and again at the end.
• One at a time, add the eggs, beating on medium-high for 1 full minute after each egg is added. Scrape down the bowl before and after adding each egg. After all three eggs are in, beat the mixture on high for 4 minutes. Seriously, set a timer here. Let the mixer do its thing. Scrape down the sides and bottom of the bowl when the 4 minutes are up.
• In a large liquid measuring cup combine the whole milk and lemon juice or vinegar (see “Notes,” below, if you’re using buttermilk). Let sit 5 minutes. Then add neutral oil and vanilla extract.
  
  With the mixer at medium speed, slowly pour the liquid mixture into the mixer bowl. Set a timer for 3 minutes — it should take you about that long to pour them in.
  
  Scrape down the sides of the bowl, then increase the mixer speed to medium-high and beat for 2-3 more minutes until the mixture is white and has almost doubled in size. The mixture should be completely homogenous with no visible streaks of fat or liquid. Scrape down the sides of the bowl again.
• In a separate bowl, mix the cake flour, cocoa powder, baking powder, and salt.
  
  With the mixer on a very low speed, use a measuring cup (1/2 c or 3/4 c recommended) to scoop and slowly add the dry mixture to the wet mixture. Once all of the dry mixture has been added and the batter comes together, don’t over mix — scrape down the sides of the bowl, then mix on low speed for 45-60 seconds to make sure there are no lumps.
• Pour the cake batter into the prepared sheet pan and use a spatula to spread it in an even layer, making sure to get it into the corners.
• Bake at 350F for 30-35 minutes. Halfway through the bake time, rotate the pan front to back. The cake will rise and puff, but ultimately settle down into a flat top. At 30 minutes, jiggle the pan slightly — the center of the cake should not be jiggly. If the center of the cake still looks jiggly, leave it in an additional 5 minutes.
• Let the cake cool completely in the pan on a wire rack or in the fridge or freezer. You want it to be completely cool before you use it, and it will be easier to remove from the pan once it’s cool. The cooled cake can be stored in the fridge, wrapped in plastic wrap, for up to 5 days.
• Chocolate Hazelnut Frosting (Day 2)
• Melt the chocolate over a double boiler, or in the microwave (10-second bursts until melted). Set aside and let cool to room temp.
• Use the stand mixer with the paddle attachment to combine softened butter, powdered sugar, cocoa powder, and salt. Set a timer for 2-3 minutes and cream at medium-high speed until smooth and fluffy. Scrape down the sides of the bowl.
  
• Reduce mixer speed as low as it can go and slowly stream in the milk. Increase the speed to medium-high and beat for additional 5 minutes (again — set a timer!). The mixture should be silky smooth and glossy. As always, scrape down the sides of the bowl.
• Add the hazelnut praline paste and cooled melted chocolate to the mixing bowl and stir on low speed until the frosting is fully combined and no streaks of chocolate or hazelnut remain.
• Transfer to an airtight container. If not using immediately, store in the fridge and re-whip using the mixer with paddle attachment at medium speed for 3-4 minutes before use.
• Hazelnut Crunch (Day 3)
• Toast the hazelnuts on an un-greased sheet pan at 350F for 10-15 minutes. To remove the skins wrap them in a dishtowel and rub them around. It’s okay if some skins are still on, but try to get most off.
• Puree the toasted hazelnuts in a food processor with the oil, brown sugar, and salt until a wet, sandy texture is achieved.
• Combine hazelnut mixture in a small bowl with crushed Frosted Flakes. Set aside.
• Chocolate Stout Ganache (Day 3)
• Combine the chocolate stout and heavy cream in a small sauce pan over medium heat. Bring to a boil.
• Meanwhile: Finely chop or grate the chocolate and place it in a heat-proof bowl.
• Pour the stout mixture over the chocolate, stirring together until completely smooth and no lumps remain.
• Use the ganache immediately. If you aren’t ready to use it right away, you can reheat it in the microwave in 15-second bursts, stirring in between.
• Coffee Soak (Day 3)
• Prepare a cup of coffee using whatever method you prefer. I use a French press, but you do you.
• Pour 1/3 cup of freshly brewed coffee into a small bowl or glass, add 3 tsp sugar and stir until dissolved.
• Assembly (Day 3)
• Use a 6″ cake cutter to cut two 6″ rounds out of the chocolate cake. Place the ring in the center of a cardboard cake round, and line it with a cake collar (a 20″ strip should be enough).
• Use the cake scraps to create the bottom layer of cake. Break them up, and crumble them with your hands, pressing them tightly into the bottom corners especially to create an even, solid foundation for your cake.
• Use a spoon or pastry brush to apply 1/3 of the coffee soak to the cake layer. Then apply 1/2 of the chocolate stout ganache, using a spatula to spread it all the way to the edges of the acetate. Top the ganache with 1/2 of the hazelnut crunch, again taking care to make sure it’s pressed up against the acetate. Finally, spread 1/3 of the chocolate hazelnut frosting over the crunch layer.
• Place the second cake layer in. If one of the two cake rounds is messier or more uneven than the other, use that one.
• Take the second 20″ acetate cake collar and insert it inside the first one. Tuck it just under the top edge of the cake layer so it stays in place.
• Now repeat the layers: 1/3 of the coffee soak, the rest of the chocolate stout ganache, the rest of the hazelnut crunch, and another 1/3 of the chocolate hazelnut frosting.
• Insert the final cake round. Place whichever side is flatter and smoother facing up. Then apply the rest of the coffee soak, and apply your final layer of chocolate hazelnut frosting.
• Take the whole thing and put it in the freezer for at least 3-5 hours, or overnight. If you plan on keeping it in the freezer for longer than overnight, cover the top with saran wrap. Before serving, take it out of the freezer and allow it to defrost for at least 3 hours. When ready to serve, remove the cake ring and peel off the acetate sheets.

Notes

• *Or, use 1/2 cup buttermilk.
• If making cupcakes, cut the amount of chocolate hazelnut frosting in half.

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