In a large oven-safe skillet, melt 2 tablespoons of unsalted butter and 1 tablespoon of olive oil over medium-low heat. Add 2 large sliced yellow onions, stirring occasionally for 30-40 minutes until they are deep golden brown and caramelized. In the last minute of cooking, add 2 minced garlic cloves for aromatic flavor and remove from heat.

While the onions are caramelizing, heat a separate skillet over medium heat. Season 2 cups of cooked shredded chicken with salt and black pepper, then add to the skillet. Brown the chicken for 3-4 minutes per side; it doesn’t need to be fully cooked at this point as it will finish baking in the French Onion Chicken Orzo Casserole.

Once the onions are caramelized, pour in 1 cup of low-sodium chicken broth, scraping the bottom of the skillet to release any browned bits. Stir in 1 cup of orzo pasta, 1 cup of heavy cream, 1 teaspoon of dried thyme, and the browned chicken. Bring the mixture to a simmer for 5-7 minutes, allowing the orzo to absorb some of the liquid.

Preheat your oven to 375°F (190°C). Stir in half of the 1 ½ cups of shredded mozzarella cheese, then pour the entire mixture into the oven-safe skillet. Top with the remaining mozzarella cheese and an optional sprinkle of grated Parmesan cheese for extra flavor. Bake for 20-25 minutes or until the top is golden and bubbly.

Once the French Onion Chicken Orzo Casserole is baked, let it rest for 5-10 minutes before serving. This allows the flavors to meld perfectly. For a finishing touch, garnish with fresh thyme or parsley if desired.