PEANUT BUTTER FILLED CHOCOLATE CUPCAKES 1 Devils Food cake mix. Make cupcakes according to box directions. Filling: beat 1 cup smooth peanut butter, 1/2 cup butter, 2 cups powdered sugar, 3 Tbls milk. Beat until light and fluffy. Cool cupcakes 5 mins. With filling tool, fill warm cupcakes with filling. Cool completely and frost with remaining filing or chocolate frosting. ENJOY!