1. Divide rice chez cereal evenly between two bowls (2 1/2 cups per bowl).
2. Add 5 oz white chocolate chips, 2 tbsp butter and peanut butter to a small microwaveable bowl. Microwave in 30 second increments until mixture is melted and smooth.
3. Add peanut butter mixture to one of the bowls of rice chex and stir carefully until all the cereal is coated.
4. Add 3/4 cup powdered sugar to the bowl and stir carefully until all the cereal is coated. Set aside to dry.
5. Add remaining 5 oz white chocolate chips, 2 tbsp butter and marshmallows to a saucepan.
6. Slowly melt over medium heat. Initially, the mixture will be clumpy, but continue to melt slowly until smooth.
7. Pour marshmallow mixture over second bowl of rice chex and stir carefully until all the cereal is coated. Mixture will be somewhat thick, so be patient and stir carefully.
8. Add remaining 3/4 cup of powdered sugar to rice chex and stir carefully until coated.
9. Combine the two bowls of puppy chow together and allow to dry.