Preheat the oven to 375°F and lightly grease a 9x13 baking dish.
In a large mixing bowl, whisk together the cream of chicken soup, milk, garlic powder, salt, and black pepper until smooth.
Add the cooked rice, cubed chicken, broccoli florets, and 1 cup of the shredded cheddar cheese to the bowl. Stir until everything is evenly coated.
Spread the mixture into the prepared baking dish and sprinkle the remaining 1 cup of cheddar cheese over the top.
Bake for 25 to 30 minutes until the cheese is melted and the edges are lightly bubbling.
Remove from the oven and let it rest for 5 minutes before serving.