Preheat the oven to 250 degrees F. Line a baking sheet with parchment.
Combine the Parmesan, butter, pecorino, garlic, Worcestershire, Italian seasoning, red pepper flakes and seasoned salt in a large bowl.
Add the rice cereal, pretzels, fruit-flavored cereal, cheese crackers and peanuts to the bowl of seasonings and toss gently. Spread the cereal mix on the prepared baking sheet.
Bake the snack mix in the oven, stirring every 20 minutes, until dried out and lightly toasted, about 1 hour.
Cool completely before serving.