Into large bowl, measure out 9 cups of Rice Chex™. 

In a microwavable bowl, microwave white 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 large plastic bag.

Add powdered sugar. Seal bag; shake until well coated. Spread on waxed paper to cool. Top with sweetened coconut flakes, mini marshmallows, and snowflake sprinkles.

Store in airtight container in refrigerator.