1-First, preheat the oven to 350 degrees F and get three 8-inch round cake pans ready by greasing them, lining with parchment paper, greasing again, and flouring. This ensures your cakes release easily and look great. In a separate bowl, sift together the dry ingredients: 2½ cups plus 1 tablespoon all-purpose flour, 3 cups granulated sugar, 1 cup plus 1 tablespoon Dutch-process cocoa powder, 1 tablespoon baking soda, 1½ teaspoons baking powder, and 1½ teaspoons salt.

2-Next, in another bowl, whisk the wet ingredients: 3 eggs at room temperature, 1½ cups buttermilk at room temperature, 1½ cups hot strong black coffee, ¾ cup vegetable oil, and 4½ teaspoons vanilla extract. Combine the wet and dry mixtures, beating on medium speed for 2 minutes, then scrape the bowl and beat for another 20 seconds. Divide the batter evenly among the pans and bake for 20 minutes, then rotate the pans and bake for another 12 minutes, or until a toothpick comes out almost clean.

3-After baking, cool the cakes in the pans for 20 minutes, then move them to cooling racks. For the peanut butter frosting, mix 2 cups powdered sugar, 2 cups creamy peanut butter, 10 tablespoons unsalted butter at room temperature, 1½ teaspoons vanilla extract, and ½ teaspoon kosher salt on medium-low speed until creamy. Beat in ⅔ cup heavy cream on high speed until light and smooth.

4-To assemble, level the cake layers if needed. Place one layer on a plate, spread with 1 cup of frosting, and sprinkle with 10 chopped peanut butter cups. Repeat for the second layer, then add the third layer face-down, coat with remaining frosting, and chill for at least 1 hour. For the ganache, warm ¾ cup heavy cream, pour over 8 ounces finely chopped semisweet chocolate, let sit for 2 minutes, then whisk until smooth and cool until pourable. Pour over the cake, let it drip, garnish with remaining peanut butter cups, and chill for 30 minutes before serving.