Preheat Oven:
Preheat your oven to 350°F (175°C). Grease a 9×13-inch baking dish or similar-sized casserole dish.
Prepare Ingredients:
Cook and shred the chicken, cook the rice, and steam the broccoli if not already done.
Mix the Base:
In a large mixing bowl, combine the cream of chicken soup, sour cream, milk, garlic powder, onion powder, salt, and pepper. Stir until smooth.
Assemble the Casserole:
Add the cooked chicken, rice, broccoli, and 1 ½ cups of shredded cheddar cheese to the bowl with the sauce. Mix until everything is well coated.
Transfer to Baking Dish:
Spread the mixture evenly in the prepared baking dish.
Add Topping:
Sprinkle the remaining ½ cup of cheddar cheese over the top. If using, combine the crushed crackers or breadcrumbs with the melted butter and sprinkle over the cheese.
Bake:
Bake in the preheated oven for 25–30 minutes, or until the casserole is bubbly and the top is golden.
Serve:
Let the casserole rest for 5 minutes before serving. Pair with a side salad or dinner rolls for a complete meal.