1. Preheat your oven to 350°F (175°C). Lightly grease a 9×13-inch baking dish with butter or non-stick spray.
2. In a large skillet, melt the butter over medium heat. Add the chopped onion and sauté for about 5 minutes, until soft and translucent. Stir in the minced garlic and cook for another minute until fragrant.
3. In a large mixing bowl, combine the cooked rice, shredded chicken, sautéed onions and garlic, frozen peas and carrots, cream of mushroom soup, sour cream, chicken broth, dried thyme, paprika, salt, and pepper. Mix everything gently until fully incorporated.
4. Pour half of the rice and chicken mixture into the prepared baking dish, spreading it evenly. Sprinkle half of the shredded cheddar cheese on top.
5. Add the remaining rice mixture on top, smoothing the surface with a spatula. Finish with the remaining cheese evenly spread over the casserole.
6. Cover the baking dish tightly with aluminum foil and bake for 25 minutes. Then remove the foil and bake uncovered for an additional 15 minutes, or until the cheese is bubbly and golden brown.
7. Once out of the oven, let the casserole rest for 5 to 10 minutes before serving. This helps the flavors meld and makes it easier to cut clean servings.

I remember the first time I made this casserole on my own after Mama Lou passed. I was nervous, hoping to honor her memory. When that golden cheese bubbled and the familiar scent filled my kitchen, I felt like she was right there, smiling beside me. It’s a simple step-by-step process that anyone can master, and trust me, the rewards are worth every minute.