In a bowl or large resealable bag, combine sweet potatoes, melted butter, olive oil, 2 tablespoons Parmesan, garlic powder, and seasoned salt. Toss to coat.
Place coated sweet potatoes onto a large baking sheet. Bake at 400 degrees F for 10 minutes. Remove pan from oven, stir. Add remaining 1 tablespoon of Parmesan. Return potatoes to oven for 8-10 more minutes until cooked and starting to brown.