Preheat oven to 250℉. Line a large rimmed baking sheet with parchment paper.
In a large bowl, stir together the Chex cereal, pretzels, Cheerios, and peanuts.
In a small bowl, stir together the butter, Worcestershire sauce and hot sauce.
In another small bowl, stir together the Cajun Seasoning, Parmesan, garlic and onion.
Pour the butter mixture over the cereal mixture, toss evenly to coat.
Add the Cajun mixture, toss evenly to coat.
Spread evenly on prepared baking sheet and bake for about 45 minutes or until everything is dry and toasted (stirring every fifteen minutes). Let cool on sheet pan.