Preheat the oven to 375°F (190°C).
Lightly grease a 9×13-inch baking dish.
In a large bowl, combine the cooked chicken, cooked rice, and steamed broccoli.
Add the cream of chicken soup, sour cream, milk, garlic powder, onion powder, paprika, salt, and black pepper.
Stir until everything is evenly coated.
Fold in 1½ cups of the shredded cheddar cheese.
Spread the mixture evenly into the prepared baking dish.
Top with the remaining cheddar cheese and Parmesan cheese.
Drizzle the melted butter over the top.
Bake for 30–35 minutes until hot and bubbly.
Broil for 2–3 minutes for a golden cheesy topping if desired.
Garnish with chopped parsley before serving.