Spray a 9x13 baking pan with cooking spray. Preheat the oven to 350 degrees Fahrenheit.
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 pan and bake for about 30-35 minutes or until the center of the cake springs back when you touch it.
Allow the cake to cool on a cooling rack. While the cake is cooling, make the frosting
Make the Frosting:
In the bowl of a stand mixer, cream together butter and peanut butter for 2 minutes.
Add 1 cup of powdered sugar and mix until blended.
Add 2 tablespoons of heavy cream and beat until completely blended.
Add in the remaining cup of powdered sugar. Beat for 1 minute.
Test the frosting and if you need another tablespoon or two of heavy cream to make the frosting spreadable, add it in.
Beat for 2-3 minutes until the frosting is light and fluffy.
*Add in ½ teaspoon of vanilla if desired.
Assemble the cake:
Use a spatula to spread the peanut butter frosting on the cooled chocolate cake.
Sprinkle with chopped candies if desired.
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. **We are not dietitians and recommend you seek a nutritionist for exact nutritional information.**