Peanut Butter Cake

1. Preheat the oven to 350°F. Line a 9 x 13 in baking pan with parchment paper.
2. In a large mixing bowl, cream together butter and sugars until smooth and pale. Add peanut butter and vanilla extract, mix until well combined. Then add eggs, one at a time, until well combined.
3. In a separate bowl, mix together baking powder, all purpose flour, cake flour, and salt.
4. Add half of the dry ingredients (step 3) and ¾ cup of milk into the wet ingredients (step 2), mix on low speed. Then add the remaining half of dry ingredients, mix until well combined.
5. Pour the cake batter into the baking pan. Bake for 25 minutes, or until the test knife comes out clean. Let cool completely.

Cake Soak

1. Whisk together milk and vanilla extract in a small bowl.

Chocolate Cookie Crumbs

1. Set the oven to 300°F.
2. Using a standing mixer with a paddle attachment, beat together sugars, cake four, baking powder, salt, softened butter, vanilla extract, and cocoa powder. The mixture will become dry and crumbly.
3. Pour the mixture onto a baking sheet lined with parchment paper. Spread the crumbs out evenly. Bake for 15 minutes. Cool completely in the pan.

Peanut Butter Buttercream Frosting

1. Using a standing mixer with paddle attachment, beat together butter, peanut butter, and 3½ cups of powdered sugar, until smooth and creamy. Add milk and vanilla extract, until smooth and combined.

Assembly

1. Put a piece of parchment on to the counter. Invert the cake onto it and gently peel off the parchment from the bottom of the cake. Use the cake ring to cut out 3 circles (2 full circles + 2 half circles) from the cake. Leave the remaining cake scraps for later. If you don't have a cake ring, you can also measure it out first and cut it by hand.
   
2. Place the cake ring onto your choice of board/plate. Line the inside of the cake ring with 1 sheet of acetate.
3. BOTTOM LAYER – Place the 2 half circles at the bottom of the cake ring. Use the cake scraps to fill any extra spaces. Use your hands to press the cake scraps together into even layer. Brush half of the cake soak into the bottom layer. Spread 1/5 of the buttercream frosting over the cake. Add 1/3 of the chocolate cookie crumbs. Then spread another 1/5 of the frosting evenly over the crumbs.
4. MIDDLE LAYER – Line the inside of the cake ring with another sheet of acetate, on top of the first sheet (high enough to support the height of the cake). Add another cake circle on top of the frosting. Brush the other half of the cake soak. Spread more buttercream frosting over, add 1/3 of the crumbs, then add another layer of frosting.
5. TOP LAYER – Add the last cake round. Cover with the remaining frosting. Garnish with 1/3 of chocolate cookie crumbs and/or chopped Reese's Peanut Butter Cups. (I ended up only using Reese's for garnish, and ate the 1/3 cookie crumb leftovers…)
6. Transfer the cake into the fridge an chill for at least 4 hours for the cake and frosting to set.
7. Before serving, gently remove the cake ring and the acetate sheet. Cut, serve, and enjoy!