- cooking spray (optional)
- 4 frozen whole chicken breasts
- 1 (8 ounce) package sliced fresh mushrooms
- 1 (10.75 ounce) can condensed cream of mushroom soup
- 8 ounces sour cream
- 1 (1 ounce) package dry onion soup mix
- Preheat oven to 375 degrees F (190 degrees C). Lightly spray the bottom of a 3-quart casserole dish with cooking spray.
- Place chicken breasts in the prepared dish and top with mushrooms. Mix cream of mushroom soup, sour cream, and onion soup mix together in a bowl; pour over chicken and mushrooms. Cover dish with aluminum foil.
- Bake in the preheated oven until no longer pink in the center and the juices run clear, about 1 hour. An instant-read thermometer inserted into the center should read at least 165 degrees F (74 degrees C).