In large microwavable bowl, mix cereal, pretzels and crackers. In small microwavable bowl, microwave butter uncovered on High about 30 seconds or until melted. Pour over cereal mixture; stir until evenly coated. Stir in dressing mix and cheese until evenly coated.
Microwave uncovered on High 3 minutes, stirring each minute. Spread on waxed paper or foil to cool. Store in airtight container.