Creating the French Onion Chicken Orzo Casserole requires a few straightforward steps. Follow this guide for successful results:

1. Preheat Oven: Preheat your oven to 375°F (190°C).
2. Sauté Onions: Heat olive oil and butter in a large skillet over medium heat. Add the sliced onions and cook, stirring frequently, until they become golden brown, about 15-20 minutes.
3. Add Garlic: Once the onions are caramelized, stir in the minced garlic and cook for an additional minute until fragrant.
4. Season Chicken: While the onions are cooking, season the chicken breasts with salt, pepper, thyme, and rosemary on both sides.
5. Cook Chicken: In the same skillet, push the onions to the side and add the chicken breasts. Sear them for about 3-4 minutes on each side until they are browned but not fully cooked through.
6. Combine with Orzo: Stir in the orzo pasta, chicken broth, and any remaining seasonings into the skillet with the onions and chicken.
7. Transfer to Casserole Dish: Pour the mixture into a greased 9×13-inch casserole dish, spreading it evenly.
8. Add Cheese: Top the casserole with shredded Gruyère and mozzarella cheese.
9. Bake: Cover the dish with foil and bake in the preheated oven for 20 minutes. Remove the foil and bake for an additional 10-15 minutes, or until the cheese is bubbly and golden.
10. Garnish and Serve: Allow the casserole to cool for about 5 minutes before garnishing with fresh parsley. Serve hot and enjoy the rich flavors.

With these easy-to-follow instructions, you’ll find making this incredible casserole a breeze. Perfect for both novices and experienced cooks alike!