Creating the French Onion Chicken Orzo Casserole is straightforward if you follow these simple steps:

1. Preheat the Oven: Preheat your oven to 375°F (190°C).
2. Cook the Onions: In a large skillet, heat the olive oil over medium heat. Add the sliced onions and cook until they are caramelized, about 15-20 minutes.
3. Prepare the Chicken: While the onions are cooking, season the diced chicken with garlic powder, thyme, salt, and pepper.
4. Sauté the Chicken: Add the seasoned chicken to the skillet with the onions. Cook until the chicken is no longer pink, about 5-7 minutes.
5. Cook the Orzo: In a separate pot, bring the chicken broth to a boil. Add the orzo and cook according to the package instructions until al dente. Drain and set aside.
6. Combine Ingredients: In a large mixing bowl, combine the cooked orzo, chicken and onion mixture, and half of the Gruyère cheese. Mix well.
7. Transfer to Casserole Dish: Pour the mixture into a greased 9×13-inch casserole dish, spreading it out evenly.
8. Top with Cheese: Sprinkle the remaining Gruyère cheese and the grated Parmesan cheese on top of the casserole.
9. Bake: Place the casserole in the preheated oven and bake for 20-25 minutes, or until the cheese is melted and bubbly.
10. Garnish: Remove from the oven and let it cool slightly. Garnish with fresh parsley before serving.

These steps will guide you in creating this incredible casserole effortlessly.