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. Transfer to the refrigerator for 20 minutes to set.