Add the Chex, Cheerios, pretzels, and peanuts the slow cooker insert. You'll need at least a 5 quart slow cooker for this recipe.
Whisk the butter, Worcestershire sauce, ground pepper, salt, smoked paprika, garlic powder, onion power, and sugar together until combined.
Pour the butter mixture over the cereal mixture.
Toss to coat the cereal mixture in the butter mixture.
Place a thin cotton towel over the opening of the slow cooker insert.
Cover and cook on low for 1 hour.
Stir, and continue cooking for 1 more hour.
Stir, and continue cooking for 30 minutes.
Stir, and continue cooking for an additional 30 minutes, for a total of 3 hours of cooking time.
Give the cereal mixture one more good stir.
Carefully spread the mix out in an even layer on large baking sheets to let it cool.
Notes
Chex cereal: I use a mix of rice, wheat, and corn Chex.
Cheerios: I use plain Cheerios.
Pretzels: Either pretzel sticks, pretzel wheels, or tiny pretzel twists work well.
Peanuts: Mixed nuts also work well. Feel free to use salted or unsalted nuts depending on how much salt you'd like the cereal mix to have.
Butter: I use salted butter, but feel free to use unsalted if you prefer.
Cloth: It's important that the cloth is thin and that it just covers the opening. This will help to prevent condensation as the cereal mixture cooks. You don't want the cloth to sit down on the inside of the slow cooker near the heating element as that could start a fire.