2. In a 1-quart microwavable bowl, microwave chocolate chips, peanut butter and butter uncovered on high 1 minute; stir. Microwave about 30 seconds longer or until mixture can be stirred smooth. Stir in vanilla. Pour mixture over cereal, stirring until evenly coated. Pour into a 2-gallon resealable, plastic, food-storage bag.
3. Add powdered sugar to bag. Seal bag: shake until well coated. Spread on waxed paper to cool. Store in an air-tight container in refrigerator.