In a bowl, combine crumbs and 2 tablespoons sugar. Stir in butter; set aside.
In another bowl, combine the flour, baking powder, salt and remaining sugar. Whisk together egg, milk and oil; stir into dry ingredients just until moistened. Place peanut butter in a microwave-safe bowl. Cover and microwave on high for 10-20 seconds or until softened. Fold into batter.
Press about 1 tablespoon reserved crumb mixture onto the bottom of 12 ungreased muffin cups. Divide batter evenly between cups. Sprinkle with remaining crumbs. Bake at 400° for 15-18 minutes or until a toothpick comes out clean. Cool for 5 minutes before removing from pan to a wire rack to cool completely.