This French Onion Chicken Casserole is a comforting, flavorful dish that combines tender chicken, caramelized onions, melted cheese, and a creamy sauce baked to perfection. It’s inspired by the classic French onion soup but transformed into a hearty dinner that’s simple to make and perfect for busy weeknights. The casserole has all the depth of flavor of the original soup—rich, savory, and satisfying—while being much easier to serve for the whole family.
If you’re looking for a cozy, crowd-pleasing meal that tastes like something straight from a French bistro, this casserole will quickly become one of your go-to favorites.
Ingredients
For the chicken:
- 3 large chicken breasts, cut into bite-sized pieces
- 1 tablespoon olive oil
- 1 teaspoon salt
- ½ teaspoon black pepper
- ½ teaspoon garlic powder
For the caramelized onions:
- 2 large yellow onions, thinly sliced
- 2 tablespoons butter
- 1 tablespoon olive oil
- 1 teaspoon sugar
- ¼ teaspoon salt
- 1 teaspoon balsamic vinegar (optional, for depth)
For the sauce:
- 1 can (10.5 oz) cream of chicken soup
- ½ cup sour cream
- ½ cup mayonnaise
- ½ teaspoon thyme (dried or fresh)
- ½ teaspoon Worcestershire sauce
- ½ teaspoon salt (adjust to taste)
- ¼ teaspoon black pepper
For the topping:
- 1 ½ cups shredded Gruyère cheese (or Swiss)
- 1 cup crispy fried onions (store-bought or homemade)
- Fresh parsley, for garnish
Instructions
- Preheat the oven:
Set your oven to 375°F (190°C). Lightly grease a 9×13-inch baking dish and set aside. - Cook the chicken:
Heat olive oil in a large skillet over medium-high heat. Add the chicken pieces, season with salt, pepper, and garlic powder, and cook until browned and cooked through (about 6–8 minutes). Remove from the pan and set aside. - Caramelize the onions:
In the same skillet, melt butter and olive oil over medium heat. Add sliced onions and cook for 10 minutes, stirring occasionally. Sprinkle sugar and salt over the onions, reduce the heat to medium-low, and continue cooking for another 20–25 minutes until deep golden brown. Stir in balsamic vinegar if using, then remove from heat. - Make the sauce:
In a mixing bowl, combine cream of chicken soup, sour cream, mayonnaise, thyme, Worcestershire sauce, salt, and pepper. Mix until smooth and creamy. - Assemble the casserole:
Add the cooked chicken to the baking dish, then spoon the caramelized onions over the top. Pour the creamy sauce evenly over the chicken and onions. Sprinkle shredded Gruyère cheese on top. - Add the topping:
Scatter crispy fried onions over the cheese layer for a golden, crunchy finish. - Bake:
Place in the preheated oven and bake uncovered for 25–30 minutes, until the cheese is melted and bubbling. - Garnish and serve:
Remove from the oven, let it rest for 5 minutes, and garnish with fresh parsley before serving.
Tips
- Use rotisserie chicken: To save time, use shredded rotisserie chicken instead of cooking your own.
- Enhance the flavor: Add a splash of white wine when caramelizing the onions for a restaurant-style flavor.
- Cheese options: If you don’t have Gruyère, you can use mozzarella, Swiss, or provolone. Gruyère, however, gives the best authentic taste.
- Crispy topping: Add the fried onions only during the last 10 minutes of baking to keep them extra crunchy.
- Make ahead: Assemble the casserole up to a day in advance, cover, and refrigerate. Bake just before serving.
- Storage: Store leftovers in an airtight container in the refrigerator for up to 3 days. Reheat in the oven for best texture.
FAQs
Can I freeze French Onion Chicken Casserole?
Yes, this casserole freezes very well. After assembling (but before baking), cover tightly with foil and freeze for up to 2 months. When ready to eat, thaw overnight in the fridge and bake as directed.
What can I serve with this casserole?
It pairs beautifully with a side of mashed potatoes, buttered noodles, rice, or a crisp green salad. Roasted vegetables like asparagus or broccoli also work great.
Can I use different meat?
Yes, you can substitute chicken with turkey or even pork chops for a variation. Just adjust the cooking time depending on the protein you use.
How can I make it lighter?
Replace the mayonnaise with Greek yogurt and use light sour cream to reduce calories while keeping the creamy texture.
Can I make it without canned soup?
Yes, simply replace the canned cream of chicken soup with a homemade version: combine 1 cup milk, 1 tablespoon flour, 1 tablespoon butter, and a pinch of salt. Cook until thickened, then mix into the sauce.
Final Thoughts
French Onion Chicken Casserole is one of those meals that instantly feels like comfort on a plate. The combination of sweet caramelized onions, creamy sauce, and melted cheese creates an irresistible harmony of flavors. It’s elegant enough for guests yet simple enough for a family dinner. Once you try it, it’s sure to become a recipe you’ll come back to again and again—especially on chilly evenings when you need something warm and satisfying.