Preheat oven to 350°F and grease a 9×13-inch baking dish with butter. Set aside.
In a medium bowl, stir together the chicken soup, celery soup, 1 can’s worth of water, and minute rice.
Transfer mixture to prepared pan.
Arrange chicken breasts on top of rice mixture, then sprinkle onion soup mix evenly over the top.
Cover dish tightly with foil, then bake until chicken is cooked through and liquid has absorbed into rice, about 90 minutes.
