Begin by preheating your oven to 350°F (175°C) to prepare for baking.
In a large mixing bowl, thoroughly combine the cooked rice, steamed broccoli florets, cream of mushroom soup, milk, and the two cheeses (sharp cheddar and Parmesan). Ensure everything is mixed uniformly for even flavor distribution.
Season your mixture generously with garlic powder, onion powder, and a pinch of salt and pepper. Stir until all ingredients are seamlessly blended.
Carefully transfer the creamy mixture into a greased casserole dish, spreading it out evenly to promote even cooking.
If you desire a crunchy topping, take a small bowl and combine the breadcrumbs with olive oil, stirring until the breadcrumbs are fully coated. Evenly sprinkle this mixture over the top of the casserole for added texture.
Place the casserole in the preheated oven and bake for 25-30 minutes. Look for it to become hot and bubbly with a beautifully golden-brown topping.
Once baked, remove the casserole from the oven and allow it to cool for about 5 minutes for easier serving.