Ingredients
- 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
- 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
- 1 cup shredded Gruyère cheese
Instructions
- Preheat the oven to 350°F (175°C).
- Caramelize the onions: In a large skillet over medium heat, melt butter with olive oil. Add onions and cook for 25-30 minutes, stirring occasionally, until deeply caramelized. Season with 1/2 tsp salt and 1/4 tsp black pepper.
- Thicken the mixture: Sprinkle flour over the onions, stir, and cook for 1 minute. Pour in the white wine and scrape up any browned bits. Let it reduce for 2-3 minutes.
- Assemble the casserole: In a 9×13-inch baking dish, combine uncooked rice, chicken stock, cooked chicken, spinach, mushrooms, thyme, garlic powder, and remaining salt and pepper. Stir to distribute evenly.
- Layer the onions: Spread caramelized onions over the rice mixture. Cover tightly with foil.
- Bake: Cook for 35 minutes. Remove foil, sprinkle Gruyère cheese over the top, and bake uncovered for 10-15 minutes until bubbly and golden.
- Rest & Serve: Let the casserole rest for 5 minutes before serving.
Notes
- Substitutions: Use Swiss, mozzarella, or cheddar instead of Gruyère.
- Make it vegetarian: Omit chicken and add extra veggies like zucchini or bell peppers.
- Spicy variation: Add red pepper flakes for heat.
- Rice alternatives: Brown or wild rice can be used, but adjust cooking time and liquid as needed.
- Prep Time: 20 minutes
- Cook Time: 45 minutes
- Category: Dinner, Casserole
- Method: Baking
- Cuisine: American, French-inspired
