Ingredients:
Cooking spray
2 ½ lb sweet onions (about 3 large onions), sliced crosswise into ¼-inch-thick slices and separated into rings
1 teaspoon dried thyme
1 teaspoon dried parsley flakes
1 teaspoon garlic salt
½ teaspoon dried oregano
½ teaspoon dry mustard
¼ teaspoon cayenne pepper
¼ cup salted butter, cut into ¼-inch-thick pieces
4 oz mild Cheddar cheese, shredded (about 1 cup)
4 oz smoked Gouda cheese, shredded (about 1 cup)
Directions:
Preheat the oven to 350°F (175°C) and spray a 9×13-inch baking dish with cooking spray.
Arrange the sliced onion rings evenly in the prepared baking dish.
In a small bowl, combine the dried thyme, parsley flakes, garlic salt, dried oregano, dry mustard, and cayenne pepper. Sprinkle this seasoning mixture evenly over the onions.
Distribute the butter pieces evenly over the onion slices.
Sprinkle the shredded Cheddar and smoked Gouda cheeses over the top of the onions.
Cover the dish with aluminum foil and bake for 30 minutes.
Remove the foil and bake for an additional 15-20 minutes, until the cheese is melted and bubbly and the onions are tender.
Let the dish cool slightly before serving.
Servings: 6-8