For the cake

Preheat the oven to 350 degrees F. Butter two round cake pans. Butter the bottom of the pan, line with parchment paper, then butter and flour the pans.

Sift the flour, sugar, cocoa, baking soda, baking powder, and salt into the bowl of an electric mixer fitted with a paddle attachment and mix on low speed until combined.

In another bowl, combine the buttermilk, oil, eggs, and vanilla. With the mixer on low speed, slowly add the wet ingredients to the dry. With mixer still on low, add the coffee and stir just to combine, scraping the bottom of the bowl with a rubber spatula. Batter will be very loose and liquid.

Pour the batter into the prepared pans and bake for 35 to 40 minutes, until a cake tester comes out clean. Cool in the pans for 30 minutes, then turn them out onto a cooling rack and cool completely.

For the frosting

Place the confectioners’ sugar, peanut butter, butter, vanilla, and salt in the bowl of an electric mixer fitted with a paddle attachment. Mix on medium-low speed until creamy, scraping down the bowl with a rubber spatula as you work. Add the cream and beat on high speed until the mixture is light and smooth.

To assemble

If the tops of the cake layers are peaked or rounded, use a serrated knife and gently level them off. If the tops of the cake layers have sunk a bit, use a little extra frosting to even them out. Place one layer right-side up on a cardboard round or a flat plate protected with strips of wax or parchment paper. Put a layer of frosting on the top of the cake, smoothing it out then invert the second cake, right-side down on top of the first.

This cake will likely require a crumb coat to seal in the crumbs before the final coat. Frost the top and sides with a thin, even layer of frosting. Don’t worry if crumbs are caught in the frosting. Place the cake in the refrigerator for 30 minutes to set. Do the final layer of frosting and decorate with the peanut butter cups as the fancy strikes you.

Place in the refrigerator to set, until ready to serve. (Remember to remove the strips of wax or parchment paper.) Enjoy!