In a large oven-safe skillet, melt 2 tablespoons of unsalted butter and 1 tablespoon of olive oil over medium-low heat. Add 3 large sliced yellow onions and a pinch of salt; cook for 30–40 minutes, stirring occasionally. The onions should turn a rich golden color and become sweetly fragrant. In the final minute, stir in 2 minced garlic cloves to enhance the aromatic flavor.

In a separate skillet, heat a drizzle of olive oil over medium heat. Season 2 cups of cooked shredded chicken with salt and pepper, then add it to the hot skillet. Brown the chicken for about 5 minutes until it is lightly golden; it does not need to be fully cooked at this stage. Remove from heat and set aside.

Pour 1 cup of low-sodium chicken broth into the skillet with caramelized onions, scraping any browned bits from the bottom. Stir in 1 cup of orzo pasta, 1 cup of heavy cream, and 1 teaspoon of dried thyme. Add the browned chicken to the mixture and simmer for 5–7 minutes, allowing the orzo to absorb some liquid while remaining al dente.

Remove the skillet from heat and mix in half of the shredded mozzarella cheese. Spread the remaining cheese evenly over the top of the mixture. Preheat your oven to 375°F (190°C) and transfer the skillet into the oven. Bake for 20–25 minutes, or until the casserole is bubbly and the cheese is golden brown.

Once the casserole is done baking, let it rest for 5–10 minutes before serving. Optionally, garnish with fresh thyme or parsley. Enjoy this comforting meal with a side salad or some crusty bread!