Preheat oven to 250F. Line a large rimmed baking sheet with parchment paper.
Combine cereal, pretzels, and crackers in a very large mixing bowl.
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.