Preheat oven to 350°F (175°C).

Butter a casserole dish.

In a saucepan, heat cream of mushroom soup, Cheez Whiz, and margarine over low heat until melted and combined, stirring frequently.

In a large bowl, combine Minute rice, thawed chopped frozen broccoli, chopped onion, and chopped celery.

Pour the soup mixture slowly into the bowl with the rice and vegetable mixture.

Mix thoroughly to ensure all ingredients are evenly coated.

Pour the mixture into the prepared casserole dish.

Bake in the preheated oven for 45 minutes, or until bubbly and golden brown.