1 (10 oz.) pkg. (about 40) regular marshmallows
1/4 c. butter
1/3 c. peanut butter
7 1/2 c. or 1 (10 oz.) pkg. Frosted Flakes cereal

Melt butter in saucepan over low heat. Add marshmallows and stir until completely melted. Remove from heat. Stir in peanut butter until mixture is smooth. Add Frosted Flakes cereal, stirring until well coated. Using a buttered spatula or waxed paper, press mixture into a lightly greased 13"x9"x2" pan. Cut into bars.