1/2cupplus 2 tablespoons (5 oz.) unsalted butterat room temperature
1 1/2cups(11 oz.) granulated sugar
1/2cup(4 oz.) buttermilk
1/2cup(4 oz.) strong coffee
For the filling
1largeover ripe bananamashed
1/2cupcreamy peanut butter
For the frosting
1/2cup(4 oz.) unsalted butterat room temperature
1/4cupchocolate flavored peanut butter
1 to 2teaspoonswhole milkif needed, to thin out frosting
3tablespoonsroasted and lightly salted chopped peanutsoptional
18dried banana chipsoptional
Heat oven to 350 degrees F.
Place 18 cupcake liners into muffin tins.
In a medium sized bowl, sift the cake flour, cocoa powder, baking soda, baking powder and salt together.
In the bowl of a stand mixer (or in a large mixing bowl), beat the butter and sugar together at high speed for 15 seconds until combined and creamy.
Add the eggs, one at a time, beating until each is incorporated. Continue beating until light and fluffy, about 6 more minutes.
With the mixer at its lowest speed, beat in one-third of the flour mixture. Beat in the buttermilk and vanilla, then another one-third of the flour mixture. Beat in the coffee and then the remaining flour mixture.
Fill the muffin cups 3/4 full and bake for 18-23 minutes, or until the centers spring back when lightly pressed. Set the pans on a rack to cool.
While the cupcakes are cooling, prepare the filling by placing the peanut butter, banana, and confectioner's sugar into a medium bowl. Use a large spoon or hand mixer on high speed to combine until no lumps remain.
Use a small spoon or apple corer to make a hole in the center of each cupcake. (Reserve the top so the hole can be covered after you've stuffed the cupcakes.)
Spoon stuffing into a piping bag fitted with a #11 tip or gallon sized plastic with the corner snipped off.
Fill each cupcake and plug the holes with reserved cupcake pieces.
For the frosting
With an electric or stand mixer, beat together the butter and peanut butter until smooth. Gradually beat in the powdered sugar until the frosting is light and fluffy. (If needed, add milk 1/2 teaspoon at a time to make the frosting smooth.)
Frost the cupcakes. Optional: Sprinkle the tops with an even amount of the chopped peanuts and garnish the tops of each cupcake with a dried banana chip.