Ingredients
Cooking spray
1 3/4 c. all-purpose flour
1 3/4 c. granulated sugar
3/4 c. unsweetened cocoa powder
1 tsp. baking powder
1/2 tsp. baking soda
1 tsp. kosher salt
1 c. buttermilk
1/2 c. vegetable oil
2 large eggs
1 tsp. pure vanilla extract
1 c. boiling water
1 c. (2 sticks) butter, softened
3 1/3 c. powdered sugar
1/4 c. heavy cream
2 tsp. pure vanilla extract
1/4 tsp. kosher salt
1/2 c. unsweetened cocoa powder
Preparation
Step 1Preheat oven to 350°. Line a 9" round cake pan with parchment and grease with cooking spray. In a large bowl, whisk together flour, sugar, cocoa powder, baking powder, baking soda, and salt. Step 2In another large bowl whisk together buttermilk, oil, eggs, and vanilla. Add dry ingredients and mix just until combined, then add boiling water. Step 3Pour batter into prepared pan and bake until a toothpick inserted into the middle comes out clean, 35 to 40 minutes. Let cool for 10 minutes, then invert onto a wire rack and let cool completely. Step 4Meanwhile, make buttercream: In a large bowl using a hand mixer, beat butter until smooth. Add powdered sugar and beat until no lumps remain. Add heavy cream, vanilla, and salt and beat until combined. Step 5Reserve 1 cup of buttercream and set aside. To remaining buttercream add cocoa powder and beat until combined. Step 6Assemble cake: Using a serrated knife, mark a line down center of cake. Cut 3/4" away from the mark on both sides, removing the center completely. Save for another use or eat now! Sandwich the two halves together by frosting the cut sides with chocolate buttercream and pushing together. Step 7Frost outside of cake with chocolate frosting and smooth with an offset spatula. Step 8Place white buttercream in a piping bag and pipe lines and laces on cake.
