ingredients Base Cake: 2 cups all purpose flour 1 1/4 tsp baking soda 1/2 tsp baking powder 1/2 tsp salt 1 1/2 cup sugar 1/2 cup oil 1 tsp vanilla 2 eggs 1 cup buttermilk Bottom Chocolate Layer: 1/4 cup + 2 tbsp cocoa powder 3 tbsp buttermilk Next Layer: 2 tbsp cocoa powder 1 tbsp buttermilk Chocolate Peanut Butter Layer: 1 1/2 tsp cocoa powder 1 tbsp creamy peanut butter Peanut Butter Layer: 3 tbsp creamy peanut butter Splash of buttermilk Peanut Butter Frosting: 1 cup butter, room temperature 1/4 cup creamy peanut butter 2 tbsp milk 2 cups powdered sugar Chocolate Frosting: 1 cup butter, room temperature 3/4 cup cocoa powder 1 1/3 cup powdered sugar 2 tbsp milk instructions Basic Cake: Preheat the oven to 350 degrees, and coat four 8 inch cake pans with cooking spray. Line pans with parchment paper. Combine flour, baking soda, baking powder, and salt in a bowl and whisk together. In another bowl, mix sugar, oil and vanilla until incorporated. Add eggs and mix well. Add flour mixture to the sugar/oil mixture alternately with the buttermilk. Mix well between additions and scrape the sides of the bowl as needed. Next, divide this batter between four bowls. The first bowl will be the bottom chocolate cake layer, so stir in 1/4 cup + 2 tablespoons of cocoa powder and 3 tablespoons of buttermilk. In the second bowl, which will be the lighter chocolate layer, stir in 2 tablespoons of cocoa powder and 1 tablespoon of buttermilk. In the third bowl, which is the chocolate peanut butter layer, stir in 1 1/2 teaspoons of cocoa powder and 1 tablespoon of creamy peanut butter. In the four and final bowl, stir in 3 tablespoons of creamy peanut butter and a little splash of buttermilk. Transfer cake batter to the prepared pans and bake for 20 minutes. Check the cakes to see if they're done by inserting a toothpick into the center of each cake. If the toothpicks come out clean, the cakes are done. Also check to see if the edges of the cake have pulled away from the sides of the pan. If the cakes aren't done, put them back in the oven for 3-5 minutes. Once the cakes are done, let them cool in the pans for about 10 minutes. Then transfer them to wire racks to cool completely. Peanut Butter Frosting: In the bowl of a stand mixer, or a medium-sized bowl with a stand mixer, beat butter and peanut butter on medium-high speed until smooth and creamy. Add milk and one cup of powdered sugar. Mix on low speed until mostly combined, and then medium speed until completely combined. Repeat with the second cup of powdered sugar. Scrape the sides of the bowl as needed. Chocolate Frosting: In the bowl of a stand mixer, or a medium-sized bowl with a stand mixer, beat butter on medium-high speed until smooth and creamy. Add cocoa powder and mix on low speed until mostly combined. Then mix on high speed until completely incorporated. Next, add milk and powdered sugar. Mix on low speed until mostly combined, then on high speed until completely combined. Assembly: Place the bottom chocolate cake layer on a cake stand or plate and cover the top with peanut butter frosting. Repeat with each of the layers, and then cover the whole cake in a crumb coat (a very thin layer of frosting that will trap all the crumbs and keep them from getting in all the rest of your frosting.) Chill the cake for 20-30 minutes, then cover the whole cake in chocolate frosting. Decorate with sprinkles if you wish!