Dear The Practical Kitchen,
Every time I make a pie or a tart, the dough seems to bubble up in the oven. The bubbles often go away, but sometimes they crack the dough and cause leaks, and other times they push the filling out of the way causing spillage. How do I stop my pie crust bubbling???
Bubble, Bubble, Toil, and Trouble
This answer was updated on 11/23/20 — click here to jump to the update.
Oh, I wish I knew what kind of pie you’re making so I could tailor this better. Some pies you bake with the filling inside from the start, and others require pre-baking (also called parbaking or blind baking) before you add the filling and finish baking (or let set in the fridge, depending on your filling).
Bubbling pie dough is caused by steam getting trapped under the dough during baking and having nowhere to go. The steam comes from the butter in the dough, which turns to liquid and then to steam in the oven.
This steam is a good thing, and is the reason why you want to keep your pie dough well chilled and avoid handling it too much before baking — in the oven, those chilled pieces of butter turn to liquid which turns to steam and creates your nice flaky layers.
When that steam has nowhere to go, however, it pushes the crust up creating bubbles and cracks. Steam is good. Bubbles are bad.
how to dock your pie dough
Regardless of if you’re pre-baking or not, it’s crucial that you dock your pie crust. Docking essentially means using a fork to poke holes all over the dough, making sure to get the sides/walls of the pie dough, too.
This allows steam to escape during baking, so it doesn’t get trapped under the dough and send your pie crust bubbling. If you’re already docking and still having issues with bubbling, you may not be docking enough.
Really make sure you’re pressing the fork to the bottom of the pan, and when you think you have enough holes, add a few more. Especially get them in corners of the crust, where the dough is likely thicker and will be more prone to bubbling and breaking.
how to use pie weights
If you’re pre-baking your crust, you can also use pie weights in addition to docking your crust to keep the dough down.
To use pie weights, you’ll want to spray a sheet of aluminum foil on one side with PAM spray or lightly grease it with a stick of butter, and press it, greased-side down into the tart crust (which should already be well-docked).
Then, scatter the pie weights, or, if you don’t have them, dry rice or beans, across the surface of the foil. Serious Eats even recommends using sugar, which takes on a toasty caramelized flavor in the oven and can be used just like regular sugar in future baking.
Pie weights come as loose ceramic beads or as a long, stainless-steel chain. I prefer the chain, because you usually have to remove the foil and pie weights from the pie part-way through the pre-bake, and it’s a lot easier to pick up a long strand of weights than it is a bunch of loose beads, if you accidentally drop them all over the bottom of your oven.
Once your pie or tart dough has baked most of the way through but is still quite pale, you’ll remove the pie weights and give it another few minutes of baking to take on some color. If you’re using a no-bake filling, you’ll finish baking it completely. If you’re using a baked filling, you’ll want to avoid letting it get too dark or else it’ll burn when you bake the filling.
UPDATE 11/23/20 — A great tip I learned in pastry school is to use parchment paper instead of aluminum foil. Crinkle the paper up into a ball, then un-wrinkle it. It will be much more flexible and sit nicely inside your pie dish.
As for deciding between parchment or aluminum foil, there’s no right or wrong here, it’s really just preference. I’ve since mostly switched to using parchment paper, as aluminum foil can be a bit sharp and if your dough isn’t frozen or well-chilled, the foil can accidentally cut through the dough.
While I still love my pie weight chain, for bigger pies I’ve come to prefer the loose beads, sugar, or a mixture of rice and beans. The pie weight chain is useful for preventing pie crust bubbling in smaller bakes, like mini cheesecakes or mini deep dish pies, but it just doesn’t distribute weight as evenly as the loose beans/rice/sugar/beads do.
To remove the pie weights, take your pie all the way out of the oven and put it on a counter or cooling rack. Then grab the edges of the paper (it won’t be hot) or use oven mitts to grab the edges of the aluminum foil. Lift it off the pie and onto the counter. Then pop the pie back into the oven.
Do not try to remove the pie weights while the pie is still on the oven rack or the oven rack has been pulled part way out of the oven. If you do this and drop your pie weights you will be extremely sad. Remove them on the counter and the worst they’ll do is roll around a bit.
Sealing your pie and tart crusts
Once you remove the pie or tart crust from the oven, brush it quickly with egg whites to seal all the holes from where you docked it. The egg white should set pretty much immediately on contact because the surface of the pie is hotter than the temperature at which eggs cook.
If it doesn’t set and dry immediately, just pop the pie crust back in the oven for 20-30 seconds. Repeat until the surface of the pie is smooth and shiny and the docking holes are entirely sealed. This will prevent the dreaded “soggy bottom” and give you a nice crisp crust.
Between the docking and the pie weights, your crust will be sure to stay down. And if, despite your best efforts, it bubbles up anyway, that’s okay — keep an eye on your pie while it bakes and if you see a bubble forming, crack the oven open and gently poke it with a knife or fork to release the steam. Then seal it up with egg whites, and no one will be the wiser.
A final tip, if all else fails: Always place your pie or tart pan on a sheet tray while you bake. That way, even if your pie dough bubbles up, or the filling leaks out or spills over the top, you won’t find yourself scraping it off the bottom of your oven later.
Recipes that use this technique: pear and gruyere tart, triple mint chocolate tart with thin mint cookie crust