The recipe I used is the Devil's Food Cake recipe found from epicurious.com. The only adjustments I made were to substitute buttermilk instead of whole milk, and adding instant espresso powder.
Devil's Food Cake
1 cup boiling water
3/4 cup unsweetened cocoa powder
1/2 cup buttermilk
1 tsp pure vanilla extract
1 tsp instant espresso powder
2 cups all purpose flour
1 1/4 tsp baking soda
1/2 tsp salt
1 cup unsalted butter, softened
1 1/4 cups packed brown sugar
3/4 cups granulated sugar
4 large eggs, at room temperature
Preheat the oven to 350 degrees. Line 2 12 cup muffin pans with liners.
Whisk together the boiling water and cocoa powder until smooth. Let cool slightly. Then, whisk in the buttermilk, vanilla, and espresso powder.
In another bowl, sift together the flour, baking soda, and salt.
In a large bowl, cream together the butter and sugars until light and fluffy.
Add the eggs one at a time, beating well after each addition. Scrape down the sides and bottom of the bowl to make sure that all the eggs were incorporated evenly into the batter.
Beat in the flour and cocoa mixtures alternately in batches, beginning and ending with the flour mixture. The batter may not be completely smooth looking.
Fill each cup about 2/3 full with the batter.
Bake the cupcakes for about 18-20 minutes, until a toothpick inserted in the center of a cupcake comes out clean.
Coffee Buttercream
2 sticks unsalted butter, softened
3-4 cups confectioner's sugar
1 tsp pure vanilla extract
1 tablespoon milk
1 tablespoon instant espresso powder
Mix together the milk and instant espresso powder.
Beat the butter at high speed until smooth. Add the vanilla extract.
Add the confectioner's sugar, one cup at a time, until you have added 3 cups. After each addition, beat until smooth.
Slowly add in the milk and espresso mixture. Only add enough to reach the desired intensity of flavor.
Add more confectioners sugar as necessary to adjust the final taste and consistency of the frosting.



