- In large bowl, add cereals; set aside.
- In 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 2-gallon resealable food-storage plastic bag.
- Add powdered sugar. Seal bag; shake until well coated. Spread on waxed paper to cool completely. Stir in M&M's™. Store in airtight container.