Preheat oven to 350 degrees. Grease and flour 2 round 9-inch cake pans.
For the cake, put flour, sugar, cocoa, baking powder, baking soda and salt in a bowl and mix well.
In a stand mixer, mix the buttermilk, oil, eggs, vanilla together. Slowly add in the mix of dry ingredients while the mixer is on low. Add the coffee and make sure everything is combined. The batter will be very thin.
Pour the batter into the prepared pans and bake for about 25 minutes or until a toothpick inserted in the middle comes out clean.
Turn the cakes out onto a cooling rack. While the cakes are cooling, make your frostings.
Peanut Butter Frosting:
In a bowl, blend together peanut butter, powdered sugar, butter, and milk 3-4 minutes or until light and fluffy.
Make the Chocolate Buttercream.
Now it's time to put your cake together!
Frost the top of the first cake with the Peanut Butter Frosting. Then layer the other half of the cake on top. Frost the outside of the cake with the Chocolate Buttercream Frosting.
Pipe flowers on top with the leftover Peanut Butter Frosting and/or decorate as desired with chopped Reese's Peanut Butter Cups.
The calories shown are based on the cake being cut into 15 pieces, with 1 serving being 1 slice of cake. Since different brands of ingredients have different nutritional information, the calories shown are just an estimate.