I took the liberty to convert the OG recipe to weight measurements .. It's been many a year since I've made this.
The Original Chex® Party Mix
3 cups Corn Chex® cereal (93g)
3 cups Rice Chex® cereal (81g)
3 cups Wheat Chex® cereal (141g)
1 cup mixed nuts (~112g*)
1 cup bite-size pretzels (~60g*)
1 cup garlic-flavor bite-size bagel chips (~60g*)
* Check serving size to adjust
6 tablespoons butter or margarine
2 tablespoons Worcestershire sauce
1 1/2 teaspoons seasoned salt
3/4 teaspoon garlic powder
1/2 teaspoon onion powder
1. In large microwavable bowl, mix cereals, nuts, pretzels and bagel chips; set aside. In small microwavable bowl, microwave butter uncovered on High about 40 seconds or until melted. Stir in seasonings. Pour over cereal mixture; stir until evenly coated.
2. Microwave uncovered on High 5 to 6 minutes, thoroughly stirring every 2 minutes. Spread on paper towels to cool. Store in airtight container.
Heat oven to 250°F. In large bowl, mix cereals, nuts, pretzels and bagel chips; set aside. In ungreased large roasting pan, melt butter in oven. Stir in seasonings. Gradually stir in cereal mixture until evenly coated. Bake 1 hour, stirring every 15 minutes. Spread on paper towels to cool, about 15 minutes. Store in airtight container.