Into large bowl, measure cereal and set aside.

In a medium microwavable bowl, microwave chocolate chips, peanut butter and butter uncovered for 1 minute; stir. Microwave 30 seconds longer or until mixture can be stirred smooth.

Stir in vanilla until combined.

Pour mixture over cereal, stirring until evenly coated.

Pour into a large ziploc bag.

Add powdered sugar. Seal bag and shake until well coated.

Spread on waxed paper to cool.

Store in airtight container.