Grama Mayse's Chicken, Rice 'n Broccoli Dish

4 cooked chicken breasts cut into bite-sized pieces
2 packages frozen broccoli florets (Birdseye is the best)
½ cup of milk
1 small onion, chopped
1 tablespoon butter
1 can of cream of chicken soup
1 jar of Cheez Whiz
1 cup of instant rice, uncooked

Cook broccoli as directed on package. Drain. Mix soup, chicken, milk, Cheez Whiz, onion, rice, butter. Add cooked broccoli. Put in a greased baking dish. Bake at 350 for 35 minutes.