• Chop and Toast Pecans. Chop 120 grams of whole pecans in a food processor or with a knife until the largest pieces are no more than ¼ inch. Place the pecans in a dry skillet over medium heat, and toast until fragrant and the smallest pieces begin to brown. Remove from the heat and divide into two containers – one with 70 grams of chopped pecans, the other with 50 grams of chopped pecans.
• Mise en Place. Bring butter and eggs to room temperature (the butter should be cool, around 65°F, but soft to the touch, not melty or greasy). Measure sugar and brown sugar for the cake batter into one container. In another container, whisk together flour, baking powder, and salt.
• Make the filling and topping. Stir 40 grams of brown sugar into the 70 grams of chopped pecans and set aside.
• Preheat oven to 325°F. Grease an 8x4" loaf pan and line it with a parchment paper sling. Set aside.
• Cream butter and sugar. Cut the butter into large chunks and place in the bowl of a stand mixer with paddle attachment. Beat on low-medium speed to soften, about 1 minute. Scrape down the bowl. Add the sugar and brown sugar, and beat on low speed until there's no loose sugar in the bowl, then increase speed to medium and continue creaming for 3-5 minutes, pausing to scrape down the bowl and the beater at least 3 times. Properly creamed, the mixture will have a fluffy, airy, and paste-like texture and pale brown color. Scrape down the sides of the bowl to finish.
• Add eggs and vanilla. One at a time, crack each egg into a small bowl (to avoid getting shells in your cake!) then dump the egg into the mixer bowl, beating on medium speed for at least 60 seconds and scraping down the bowl again before adding the next egg. Add the vanilla along with the last egg. Scrape down the bowl again after the last egg and vanilla have been added.
• Alternate adding dry ingredients and sour cream. Add half the dry ingredients and mix on low speed until just barely combined. Scrape down the bowl and beater. Add the sour cream and mix on low just until combined, then stop and scrape the bowl and beater again. Add the remaining dry ingredients on low speed until just a few streaks of flour remain. Do not over mix!
• Add pecans. Add the 50 grams of chopped pecans to the cake batter. Use a spatula to scrape down the sides of the bowl and gently fold them into the cake batter until evenly distributed and all the remaining streaks of flour are incorporated.
• Assemble. Scoop 400 grams of batter into the parchment-lined loaf pan. Use a mini offset spatula to smooth out the batter, pressing it down into the corners and sides of the pan so that there aren't any trapped air bubbles. Sprinkle about three-quarters of the brown sugar pecan filling evenly over the batter. Scoop the remaining batter on top and level off the top so it's smooth. Top with the remaining brown sugar pecan mixture and press a few whole pecans into the top of the cake for a final flourish.
• Bake. Bake in the center of a 325°F oven for 75-85 minutes, until a toothpick inserted in the center comes out with just a few crumbs clinging to it, or an internal temperature of 200°F.
• Cool. Remove the pan to a cooling rack. Let cool 15-20 minutes, then use the parchment sling to lift the cake out of the pan to finish cooling. Let cool completely before adding icing.

White Icing Drizzle

• White icing drizzle. Whisk together the sifted powdered sugar, vanilla bean extract, and milk to create an icing. Use a fork or a piping bag with a small hole at the tip to drizzle white icing in a zig-zag across the top of the cake. The drizzle will harden as it sets.