Onion Ring Chips Instructions Preheat the oven to 400F and line a sheet pan with Parchment paper. Using a Mandolin slicer, slice the 4 small onions thin (1/4 inch thickness) Spread the 8 ounces shredded Parmesan Cheese over the prepared sheet pan. Carefully line the sliced onions over the parmesan cheese. Spray with cooking oil spray and season with the 1 teaspoon smoked paprika, 1 teaspoon onion powder, and 1 teaspoon garlic powder. Bake for 18-20 minutes or until the cheese turns golden brown.