Preheat oven to 350 degrees.
In a big bowl combine chex, Cheezits, and pretzels.
Add melted butter and mix well.
Sprinkle little bit of Ranch dressing seasoning mix and stir well until package contents are gone.
Add parmesan cheese and mix until evenly coated.
Take a baking sheet and cover with tin foil.
Place half of mix on baking sheet and spread evenly; bake in oven for 5 minutes, let cool.
Repeat with remaining chex mix.
Store in airtight container.
Recipe taken from Chex.com- Directions modified by Susan S.