Preheat your oven to 250°F (120°C). This low temperature is crucial because it dries out the cereal and sets the sauce without burning the delicate ingredients. Line a large roasting pan or a rimmed baking sheet with parchment paper for easy cleanup.

In a very large mixing bowl, combine the Corn Chex, Rice Chex, Wheat Chex, pretzels, peanuts, and rye chips. Gently toss them with your hands or a large spoon to ensure an even distribution of all the different textures.

In a small microwave-safe bowl, melt the butter. Whisk in the BBQ sauce, Worcestershire sauce, brown sugar, smoked paprika, garlic powder, onion powder, and cayenne pepper. Stir until the sugar is dissolved and the sauce is smooth and well-combined.

Slowly pour the BBQ butter mixture over the cereal blend. Use a large spatula to gently fold the mixture together. Keep tossing until every piece of cereal and nut is evenly coated with the sauce. Be careful not to crush the cereal pieces as you mix.

Spread the mixture in an even layer onto your prepared baking sheet. Place it in the oven and bake for 45 minutes. It is very important to stir the mix every 15 minutes to ensure it dries evenly and doesn’t stick to the bottom.

Remove the pan from the oven. The mix might still feel a little soft, but it will crisp up significantly as it cools. Allow it to cool completely on the pan before moving it to a serving bowl or storage container.