To bake the French-onion chicken casserole, heat the oven to 400F (200C). Lightly grease an 9x12-inch baking plate and set aside.
Warm butter in a large pan over medium-high heat. Season with salt. Cook for 5-8minutes or until soft.
Heat on medium until onions are caramelized, about 15 minutes. Keep stirring until the onions turn golden brown.
Add the fresh minced garlic. Cook for approximately one minute. Let the mixture cool slightly after you turn off the heat.
Season chicken breasts by adding crushed chili pepperflakes, oregano, salt, pepper, and garlic spice. French onion and French cheese come already salted, so it's best to not add salt. Arrange the breasts of chicken in the baking dish.
6 Spread caramelized onions onto each chicken breast. Sprinkle the cheese with some salt and pepper and bake in the oven for about 20-25 minutes, or longer, depending upon the thickness of your chicken breasts. Broil the cheese for two minutes. To serve, garnish the French onions chicken casserole and add fresh chopped Parsley. Enjoy!