01 -
Preheat the oven to 375°F (190°C).
02 -
Peel the onions and slice them into ¼-inch-thick rounds. Gently separate them, keeping the rings mostly intact.
03 -
Grease a baking dish and layer the onion slices evenly across the bottom.
04 -
In a bowl, combine the cheddar, mozzarella (or Monterey Jack), and Parmesan cheeses.
05 -
Sprinkle the cheese mixture generously over the onions.
06 -
Drizzle the melted butter evenly over the top.
07 -
Season with garlic powder, salt, black pepper, and dried herbs.
08 -
Cover loosely with foil and bake for 20 minutes.
09 -
Remove the foil and bake an additional 15 minutes, until bubbly and golden brown on top.
10 -
Let rest for 5 minutes before serving. Garnish with parsley if desired.