In large microwaveable bowl, mix cereals. Line cookie sheet with waxed paper or foil.
In 2-cup microwaveable measuring cup, microwave butter, peanut butter and brown sugar on High about 1-2 minutes, stirring after 1 minute, until mixture is boiling. Pour over cereal, stirring until evenly coated.
Microwave uncovered on High 4 minutes, stirring and scraping bowl every minute. Microwave uncovered on High 2 more minutes, just until cereal begins to brown. Immediately stir in half of the chips; cool 5 minutes, stir in remaining chips.
Spread on waxed paper or foil to cool. Store in airtight container.