1. Combine 1/4 cup each peanuts and mini chocolate chips in a mini chopper and pulse until chopped. Fold into vanilla batter. To frost: Beat together 1/4 cup peanut butter, 1/4 cup (1/2 stick) softened unsalted butter, 2 cups confectioners sugar, 3 tbsp milk and 1/8 tsp salt. Spread over cupcakes and garnish with 12 mini Reeses peanut butter cups, unwrapped and chopped.