01 -
Preheat your oven to 350°F (175°C).
02 -
Coat a 9×13-inch baking dish with non-stick cooking spray.
03 -
Clean and peel the Vidalia sweet onions. Slice them into rounds approximately ¼ inch thick, ensuring to keep the rounds intact.
04 -
Spread the onion rounds evenly across the base of the prepared baking dish. Season with salt, garlic powder, and oregano. Distribute the butter pats evenly across the seasoned onion rings.
05 -
Sprinkle the Italian blend cheese and cheddar cheese evenly over the onion rings. Top with shredded Parmesan cheese.
06 -
Place the baking dish into the preheated oven. Bake for 35-40 minutes until the cheese is browned and bubbling.
07 -
For optimal taste, serve the dish promptly while it remains warm.