In a mixing bowl, combine 1 can cream of chicken, 1 1/2 cups instant white rice, 1 1/2 cups water, 1/2 cup diced onion.
(If you use regular uncooked rice, then just add another cup of water.)
Spread mixture on bottom of casserole dish.
Then add slices of raw chicken breast and broccoli pieces.
Bake covered at 375 for 45 minutes.
Add cheddar cheese to the top and bake another 10 minutes uncovered.