Preheat your oven to 350°F (175°C).
In a large mixing bowl, combine cooked rice and broccoli florets.
Add the cream of mushroom soup and milk to the bowl.
Stir in garlic powder, onion powder, salt, and pepper.
Mix in 1/2 cup of shredded cheddar cheese.
Transfer the mixture into a greased 9x13-inch baking dish.
In a separate bowl, mix breadcrumbs with melted butter.
Sprinkle the breadcrumb mixture evenly over the casserole.
Top with the remaining shredded cheddar cheese.
Bake in the preheated oven for 25-30 minutes or until bubbly and golden.