Preheat your oven to 350°F (175°C). While the oven warms up, you can start preparing the casserole ingredients.
If you’re using fresh broccoli, steam or blanch it for 3–4 minutes until it’s bright green and slightly tender. For frozen broccoli, you can microwave it for about 3–5 minutes until thawed.
In a large mixing bowl, combine the cream of mushroom (or chicken) soup, sour cream, mayonnaise, garlic powder, onion powder, salt, and pepper. If you’re using Cheese Whiz, now’s the time to stir it in.
Add the steamed broccoli to the cheese mixture and gently fold it together. If you’re adding cooked rice to the casserole, mix it in at this step.
Lightly grease a 9×13-inch baking dish with butter or non-stick spray. Pour the broccoli and cheese mixture into the dish, spreading it evenly.
For a crispy, buttery topping, mix the crushed Ritz crackers with the melted butter in a small bowl. Sprinkle this mixture evenly over the top of the casserole.
Place the dish in the preheated oven and bake for 25–30 minutes, or until the casserole is hot, bubbly, and golden brown on top.