Preheat oven to 350°F and line two cupcake tins with cupcake liners (or use one pan, two batches). Using a stand mixer fitted with the paddle attachment (or a large mixing bowl with a hand mixer), combine the butter and sugars and beat on medium speed for 2 minutes. Add the eggs and vanilla and beat on medium-low speed for 30 seconds.
In a separate bowl, combine the flour, cocoa powder, baking powder, baking soda and salt. Mix well. Gradually add to the butter mixture and beat on medium-low speed until just combined. Add the coffee and buttermilk and mix until just combined.
Fill each cupcake liner half full of batter and bake in the preheated oven for 18-22 minutes, or until a toothpick inserted into the centers come out clean. Let cool. Prepare the Chocolate Ganache Frosting while the cupcakes are baking and cooling.
Spread the frosting onto the cupcakes, add sprinkles (if desired) and serve!
Notes
Using buttermilk for this recipe is key! If you replace it with another wet ingredient such as milk or cream, your cupcakes may need to be transformed into Cupcake Truffles. Make sure the buttermilk is at room temperature before adding it to the batter and give it a vigorous shake just before adding it to the batter.
Filling the cupcake liners much more than halfway full will result in cupcake disaster. A lot of cupcake recipes work well with 3/4 full liners, but not this one. GO HALF FULL!
Baking these cupcakes for 20 minutes resulted in perfection in my oven, but test using the toothpick method starting at the 18-minute mark.