PREPARATION:

1. Preheat oven to 350°F. Line 18 standard (2-1/2-inch) muffin pan cups with foil baking cups.
2. Beat butter and peanut butter in large bowl with electric mixer at medium speed until smooth; beat in sugars until well mixed. Beat in eggs and vanilla.
3. Combine flour, baking powder and salt in medium bowl. Add flour mixture to peanut butter mixture alternately with milk, beginning and ending with flour mixture.
4. Spoon batter into prepared muffin cups, filling 2/3 full. Bake 23 to 25 minutes or until cupcakes spring back when touched and toothpicks inserted in centers come out clean. Cool in pans on wire racks 10 minutes. Remove cupcakes to racks; cool completely.
5. Prepare Peanut Butter Chocolate Frosting. Frost each cupcake with about 1-1/2 tablespoons frosting. Garnish as desired.