In large microwaveable bowl, mix cereal, pretzels, and crackers. In a small microwaveable bowl, microwave butter uncovered on high about 30 seconds or until melted. Pour over cereal mixture, stir until evenly covered. 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.