Preheat the oven to 250 deg. Pour pretzels onto two sheet pans.
Whisk melted butter, oil, ranch seasoning, garlic, cajun seasoning, and onion powder. Pour over pretzels and mix to combine.
Sprinkle parmesan and mix again.
Bake until dry and crunchy (30-45 min), stirring every 15-20 min. Let cool completely and store in a sealed container.