Preheat the oven to 375°F and lightly grease a medium baking dish.
Prepare fresh or thawed broccoli and drain excess water.
Mix cream of chicken soup, milk, garlic powder, salt, and black pepper until smooth.
Stir cooked chicken and rice into the creamy sauce until evenly coated.
Fold in broccoli, then mix in 1 cup cheddar cheese.
Spread the mixture evenly in the baking dish and top with remaining cheddar.
Mix breadcrumbs with melted butter and Parmesan, then sprinkle over the top.
Bake for 25 to 30 minutes until hot and bubbling.
Broil for 1 to 2 minutes if needed for a golden topping, watching closely.
Rest for 5 minutes and serve warm.