Prepare the broccoli by blanching it in boiling water for 3 minutes.

In a large bowl, combine the cooked rice, cream of mushroom soup, milk, garlic powder, salt, and pepper.

Add the blanched broccoli and 1 cup of cheddar cheese to the mixture, stirring until combined.

Transfer the mixture to a greased baking dish and spread evenly.

Sprinkle the remaining cheese and breadcrumbs mixed with melted butter over the top.

Bake in a preheated oven at 350°F (175°C) for 25-30 minutes or until bubbly and golden.

Let the casserole cool for 5 minutes before serving.