1. Preheat the Oven: Start by setting your oven to 375°F and lightly greasing a 9×13-inch baking dish.

2. Sauté the Aromatics (Optional): If you’re using onions and garlic, sauté them in a small skillet over medium heat until the onions are translucent, about 3-4 minutes. Then, add the garlic and cook for another 30 seconds.

3. Mix the Base Ingredients: In a large mixing bowl, combine the uncooked rice, chicken broth, milk, sautéed onions and garlic (if using), salt, pepper, and thyme. Stir until everything is well incorporated.

4. Fold in the Good Stuff: Add the shredded chicken, sliced carrots, frozen peas, and half of the shredded cheese to the rice mixture. Gently fold everything together until it’s evenly distributed.

5. Transfer to the Baking Dish: Pour the chicken and rice mixture into the prepared baking dish and smooth it into an even layer. Sprinkle the remaining cheese over the top.

6. Cover and Bake: Tightly cover the dish with aluminum foil or a casserole lid and bake for 45-50 minutes, or until the rice is tender and most of the liquid has been absorbed.

7. Uncover and Broil (Optional): For a golden, bubbly cheese topping, remove the foil during the last 5-10 minutes of baking and switch your oven to the broil setting. Keep a close eye on it to prevent burning.

8. Rest and Garnish: Once the casserole is out of the oven, let it rest for 5-10 minutes before serving. Garnish with fresh parsley or chives, if desired.