1. Preheat your oven to 375°F (190°C). Lightly grease a 9×13-inch baking dish and set aside.
2. Heat 1 tablespoon of olive oil in a large skillet over medium heat. Add the sliced onions with a pinch of salt and cook slowly, stirring occasionally, for about 30-35 minutes until the onions are deeply caramelized and golden brown. This step is key—it brings out that rich, sweet flavor that defines French onion dishes. If you’re short on time, a pinch of sugar can speed caramelization, but I prefer the slow method my grandmother taught me.
3. Once the onions are caramelized, add the minced garlic and thyme. Cook for another minute until fragrant, then transfer the mixture to a bowl.
4. In the same skillet, heat the remaining tablespoon of olive oil over medium-high heat. Add the chicken pieces, season with salt and pepper, and cook until browned but not fully cooked through, about 4-5 minutes. They’ll finish cooking in the oven.
5. In the prepared baking dish, combine the browned chicken, caramelized onions and garlic, uncooked orzo, beef broth, and white wine (if using). Stir well to combine.
6. Sprinkle half of the Gruyère cheese and Parmesan over the top. Dot with butter to help create a lovely golden crust.
7. Cover the dish tightly with foil and bake for 25 minutes. Then remove the foil and bake uncovered for another 10-15 minutes, or until the orzo is tender, the chicken is cooked through (internal temp should reach 165°F), and the cheese is bubbly and golden.
8. Remove from oven and let it rest for 5 minutes before serving. Sprinkle with fresh parsley for a pop of color and freshness.

I remember the first time I let this casserole rest after baking—it’s tempting to dive right in, but that little pause lets the flavors marry and the orzo soak up every last bit of broth. It’s worth the wait, trust me.