Heat oven to 250° F. Spray 13 x 9-inch baking pan with cooking spray.
Combine cereal and pretzels in pan; mix well. Place butter in 2-cup microwaveable bowl. Microwave on HIGH 45 seconds or until melted.
Stir in mustard, honey, garlic powder, onion powder and salt; mix well. Pour over cereal mixture; stir to coat evenly.
Bake 1 hour, stirring every 15 minutes. Transfer to baking sheet, spreading mixture in even layer. Cool completely.
Store tightly covered at room temperature up to 5 days.
Servings: 10 cups