10 tablespoons (1 1/4 sticks) unsalted butter at room temperature
1 1/2 cups sugar
3 large eggs
1/2 cup buttermilk
1 teaspoon vanilla extract
1/2 cup brewed strong, hot coffee
1/2 cup unsalted butter at room temperature
1 cup creamy peanut butter
1 1/4 cups sifted confectioners’ sugar
5 ounces semisweet chocolate, coarsely chopped
3/4 cup heavy cream
Instructions
Make the Devil’s Food cake: Set a rack in the middle of the oven and preheat to 350 degrees. Generously coat a 12-slot muffin tin with nonstick vegetable spray. Into a large bowl, sift the flour, cocoa, baking soda, baking powder, and salt together, three times. In a mixing bowl, beat the butter and sugar together at high speed for 15 seconds, until combined. Add the eggs, 1 at a time, beating until each is incorporated. Continue beating until light and fluffy, about 6 minutes more. With the mixer on its lowest setting, beat in a third of the flour mixture. Beat in the buttermilk and vanilla, then another third of the flour. Beat in the coffee and then the remaining flour. Fill the cups of the muffin tin 2/3 full and bake 15 minutes, or until the centers spring back when lightly pressed and a cake tester comes out clean. Set the pan on a rack to cool.
For the Peanut Butter Buttercream Filling: Beat the butter and peanut butter in a mixing bowl until blended. Reduce the speed to low and gradually beat in the confectioners’ sugar. Increase the speed to high and beat for 3 to 5 minutes until smooth and fluffy. Scrape the Peanut Butter filling into a pastry back fitted with 1/4-inch plain tip. With a small knife, carefully carve a 1-inch round by 1-inch deep plug out of the bottom of cupcakes, you’re going to need the plug to refill the hole, so don’t chuck it out. Fill with peanut butter cream. Cut a 1/4-inch disk off the cake plug and cover the exposed cream.
For the Ganache Frosting: Put the chocolate in a small bowl. In a small saucepan, over medium heat, bring the cream just to the simmering point. Pour the hot cream over the chocolate and, working from the center out, gently stir with a whisk to melt the chocolate and blend until smooth.
Dunk the cupcakes into the frosting to coat, then place on a rack, frosted side up. Transfer to the refrigerator for up to 20 minutes to set before serving.