Preheat your oven to 350°F (175°C). Lightly grease a 9×13-inch baking dish with non-stick spray or a thin layer of butter to prevent sticking.

In a large mixing bowl, combine 3 cups chicken broth, 2 cans of cream of celery soup, and 1/4 cup melted butter. Whisk together until smooth.

Add 2 cups of uncooked white rice and 2 cups of cubed chicken to the sauce mixture. Season with salt, pepper, and 1 teaspoon of garlic powder. Stir until everything is well coated.

Pour the chicken and rice mixture into the prepared baking dish, spreading it out evenly. Cover the dish with aluminum foil to trap moisture.

Place the covered baking dish in the preheated oven and bake for 70 minutes. After 70 minutes, remove the foil. The rice should be tender, and the chicken should be cooked through.

Sprinkle 1 cup of grated cheddar cheese evenly over the casserole. Return to the oven, uncovered, and bake for an additional 10 minutes until the cheese melts and browns.

Remove the casserole from the oven and let it rest for a few minutes to set. Serve warm with a green salad or steamed vegetables.