Heat oven to 375º and spray cookie sheet with cooking spray.
Reserve 1/3 C. frosting. In a large bowl combine remaining frosting, peanut butter, and egg. Blend well. Stir in flour.
Shape dough into 1" balls; flatten each with a glass dipped in sugar, and bake for 6 minutes. Do not overbake.
Cool and frost with remaining frosting.
Optional-sprinkle with chopped peanuts.
Recipe submitted by florentine on 12/15/99