Note about coffee and espresso powder in chocolate cakes. Coffee enhances the flavor of chocolate. I would suggest to use it. Sometimes, if may be a strong taste. You can cut down the amount you use. If it is powder you can use less, if it is coffee like in this recipe you can use 1/2 coffee and 1/2 water, but you do need the liquid for the recipe. I would suggest to try the recipe as is and if you find the coffee flavor is too strong write notes and use less next time.
1 1/4 Cups cake flour
1/2 Cup Dutch processed unsweetened cocoa powder
1 Teaspoon baking soda
1/4 Teaspoon baking powder
1/2 Teaspoon salt
1/2 Cup plus 2 tablespoons (1 1/4 sticks) unsalted butter, at room temperature
1 1/2 Cups granulated sugar
3 Large eggs
1/2 Cup buttermilk
1 Teaspoon vanilla extract
1/2 Cup strong, hot coffee
Peanut Butter Buttercream Filling:
1/2 Cup unsalted butter, at room temperature
1 Cup creamy peanut butter
1 1/4 Cups sifted confectioners' sugar
Ganache Frosting:
4 Ounces semisweet chocolate, coarsely chopped
1/2 Cup heavy cream
1 Cup roasted peanuts, chopped (optional)
Directions
- Set rack in the middle of oven and preheat to 325 degrees F. 
- Line a 12 slot muffin pan with large paper or foil cupcake liners. 
- Sift the flour, cocoa, baking soda, baking powder and salt together 3 times. 
- In the bowl of an electric mixer, 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 longer. 
- With the mixer at its lowest speed, beat in 1/3 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 sections of the muffin tin 1/2 full and bake for 15 minutes or until the centers spring back when lightly pressed. Set pan on a rack to cool. 
Peanut Butter Buttercream Filling:
- Beat the butter and peanut butter at medium speed in a mixing bowl until blended. 
- Reduce speed to low and gradually beat in the confectioners' sugar. Increase speed to high and beat for 3 to 5 minutes until smooth and fluffy. 
- Fill a pastry bag fitted with a medium, plain tip with filling. 
- Insert tip into each cooled cupcake and squeeze approximately 3 tablespoons of filling into each cupcake. 
Ganache Frosting:
- Place chocolate in a medium bowl. 
- Bring the cream to a scald in a small saucepan. 
- Pour cream over chocolate and let sit 1 minute, then whisk until smooth. 
- Let sit for 10 minutes until thick, but still pourable. 
- Dunk the top half of the cupcakes into the frosting to coat, then place on a rack and sprinkle with the chopped peanuts (optional). 
- Transfer to the refrigerator for 20 minutes to set.