Whisk together the oil, powdered ranch, garlic powder, and cajun seasoning.
Pour the mixture over the pretzels in the roasting pan and stir to coat.
Sprinkle with grated parmesan and stir to coat.
Stir the pretzels every 15 minutes for three hours, or until the oil is absorbed. (No need to turn the oven on!)
Video
Notes
The bag of pretzels I purchased contained 24 ounces of pretzels, so as the woman from the grocery store suggested, I added a few of handfuls of pretzels from another bag.