Spoon frosting into large microwable bowl; add butter. Microwave uncovered on High 1 minute 30 seconds. Stir well; microwave 1 minute longer or until melted and hot. Sprinkle chocolate chips over hot mixture. Do not stir. Microwave on High 30 seconds. Let stand 2 to 3 minutes or until chips are melted. Stir to blend. Stir in cereal and peanuts.