In large bowl, measure out cereal and set aside.
In 1-quart microwavable bowl, microwave white chocolate chips, peanut butter and butter uncovered for about 1 minute then stir. Microwave about 30 seconds longer or until mixture can be stirred smooth. Stir in vanilla. Pour mixture over cereal, stirring until evenly coated.
Add half of the powdered sugar into 2-gallon resealable zip lock plastic bag, pour cereal mixture into bag and then add remaining powdered sugar. Seal bag. Shake until well coated.
Spread on waxed paper to cool and dry. Add in all your candy and store in airtight plastic container in refrigerator.