Preheat oven to 375F (190C). Spray a 9 x 13-inch baking dish with cooking spray.
Add cream of chicken soup and water to the prepared dish. Whisk together until completely combined.
Stir in uncooked rice, uncooked chicken, and frozen broccoli. Season with about ½ teaspoon salt and ¼ teaspoon pepper. Stir again.
Cover tightly with foil and bake for 1 hour, or until the liquid is absorbed, the rice is tender, and the chicken is cooked through. If desired, sprinkle the top of the casserole with grated cheese and return to the oven for a few more minutes, just until the cheese is melted.
Notes
Cooking Just for Two? Cut the ingredients in half and bake the casserole in an 8-inch square pan!*Rachel's original recipe did not include the cheese. I just think it's a nice addition on the top, so add as much (or as little) cheese as you like -- it's certainly not necessary!