Description

This French Onion Chicken & Rice Casserole combines the rich, deep flavors of caramelized onions and Gruyère cheese with tender chicken, mushrooms, and spinach, all baked into a creamy and comforting one-dish meal. Perfect for a hearty family dinner, this casserole features a savory blend of herbs, chicken stock, and white wine that elevates the classic rice casserole to a gourmet level.

Ingredients

Scale

Sauce and Onions

4 tbsp unsalted butter
2 tbsp olive oil
2 large sweet onions, thinly sliced
1 tsp salt, divided
1/2 tsp black pepper, divided
1 tbsp all-purpose flour
1/2 cup dry white wine

Casserole Base

1 cup uncooked long-grain white rice
2 cups chicken stock
2 cups cooked chicken, shredded or diced
1 cup fresh baby spinach
1 cup sliced mushrooms
1/2 tsp dried thyme
1/4 tsp garlic powder

Topping

1 cup shredded Gruyère cheese

Cook Mode Prevent your screen from going dark

Instructions

Preheat Oven: Preheat your oven to 350°F (175°C) to prepare for baking the casserole.
Caramelize Onions: In a large skillet over medium heat, melt the butter with olive oil. Add the thinly sliced sweet onions and cook for 25-30 minutes, stirring occasionally until they are deeply caramelized and golden brown. Season the onions with 1/2 teaspoon salt and 1/4 teaspoon black pepper during cooking to enhance their flavor.
Thicken Onion Mixture: Sprinkle the all-purpose flour over the caramelized onions and stir well, cooking for about 1 minute to remove the raw flour taste. Pour in the white wine, scraping the bottom of the skillet to loosen any browned bits, and let the mixture simmer and reduce for 2-3 minutes until slightly thickened.
Assemble Casserole Mixture: In a 9×13-inch baking dish, combine the uncooked long-grain white rice, chicken stock, cooked chicken, fresh baby spinach, sliced mushrooms, dried thyme, garlic powder, and the remaining 1/2 teaspoon salt and 1/4 teaspoon black pepper. Stir well to ensure all ingredients are evenly distributed.
Layer Onions: Spread the caramelized onion mixture evenly over the rice and chicken mixture in the baking dish. Cover the dish tightly with foil to trap moisture for even cooking.
Bake Covered: Place the casserole in the preheated oven and bake covered for 35 minutes, allowing the rice to cook through and flavors to meld.
Add Cheese and Bake Uncovered: After 35 minutes, remove the foil and sprinkle the shredded Gruyère cheese evenly over the top of the casserole. Return the dish to the oven and bake uncovered for an additional 10-15 minutes, or until the cheese is bubbly and golden brown.
Rest and Serve: Remove the casserole from the oven and let it rest for 5 minutes before serving. This helps the dish set and makes it easier to serve.

Notes

You can substitute Gruyère cheese with Swiss or mozzarella if preferred.
Using homemade chicken stock will enhance the casserole’s flavor, but store-bought can be used for convenience.
If you want to make it ahead, assemble the casserole up to the point before baking, cover tightly, and refrigerate for up to 24 hours before baking.
For extra creaminess, stir in 1/4 cup of sour cream or cream cheese into the rice mixture before baking.
Leftovers can be stored in an airtight container in the refrigerator for up to 3 days and reheated gently in the oven or microwave.