1. Preheat oven to 350 degrees
  2. Grease 9 inch square baking pan and set aside
  3. In saucepan melt butter and chocolate over low heat in a double boiler. Set aside and let cool slightly.
  4. In mixing bowl beat eggs and sugar until light and pale colored.
  5. Add flour and slightly cooled melted chocolate and stir well.
  6. Pour mixture into 9 inch baking pan and bake at 350 degrees for 25 minutes or until wooden pick comes out clean. Cool in pan on wire rack
  7. Beat icing sugar, peanut butter, vanilla and butter in mixing bowl.
  8. Stir in milk until mixture achieves spreading consistency and spread over cooled brownies. Cover and refrigerate until firm.