Start by preparing the ingredients. Cook the rice according to package instructions and set it aside. Steam the broccoli until tender, about 4–5 minutes, then drain and set aside. Preheat the oven to 350°F (175°C) and grease a 9x13-inch baking dish.
Next, make the cheese sauce. In a medium saucepan over low heat, melt the Cheese Whiz and stir in the milk until smooth. Add the cream of mushroom soup, garlic powder, onion powder, salt, and black pepper. Stir well until fully combined and creamy.
Now, assemble the casserole. In a large mixing bowl, combine the cooked rice, steamed broccoli, and cheese sauce, stirring until everything is evenly coated. Transfer the mixture into the greased baking dish, spreading it evenly to ensure consistent baking.
For extra flavor, add toppings. Sprinkle shredded cheddar cheese over the top for extra cheesiness. If desired, add French fried onions or crushed Ritz crackers for a crispy, golden topping that adds a delicious crunch.
Bake the casserole in the preheated oven for 25–30 minutes, or until the dish is bubbling and golden brown on top. Once done, remove it from the oven and let it rest for 5 minutes before serving to allow the flavors to settle.