Make whichever chocolate cake recipe you'd like for this recipe and cool completely to room temperature.
For the frosting, stir softened butter and peanut butter together. Add in vanilla, powdered sugar and salt. This mixture should slowly start to come together and be very crumbly/thick. That's your cue to add in the milk!
Slowly drizzle in 1 tablespoon milk to create a thick frosting. Add in more or less depending on the consistency you're going for. Once it's smooth, thick and creamy, it's ready to use.
Place one round chocolate cake on a serving platter. Spread a skinny layer of frosting over cake, pushing extras to the edges. Top with second cake and frost cake completely with remaining frosting. It should be the perfect amount!
Garnish with ridiculous amounts of peanut butter cups and drizzle edges with chocolate sauce. Serve as you like.