3 cups (1/2 of 10-1/2-oz. pkg.) miniature marshmallows
1/2 cup peanut butter, divided
4 cups Honey Bunches of Oats Cereal
4 squares semi-sweet chocolate
Grease 8-inch square pan lightly. Microwave butter and marshmallows in large microwaveable bowl on high 30 sec.; stir. Microwave 30 sec. or until marshmallows are melted when stirred.
Reserve 2 Tbsp. peanut butter for frosting; set aside. Stir remaining peanut butter into marshmallow mixture. Immediately add cereal; toss until well coated. Press mixture into prepared pan.
Microwave chocolate and reserved 2 Tbsp. peanut butter in microwaveable bowl 1 to 1-1/2 min., stirring after 30 sec. Stir until chocolate is completely melted and mixture is smooth. Pour over cereal mixture; spread to cover. Refrigerate 15 min. until frosting is set. Cut into 16 squares.