Chinese Chicken Casserole

2 cups chopped onion
1 can bean sprouts, drained
1 can bamboo shoots, drained
1/2 cup soy sauce
6 boned chicken breasts
2 cups celery slices
1 can water chestnuts, drained
1 can mushroom pieced and stem, drained
1 can mushroom soup
1 can beef boullion

layer all ingredients in slow pot, mix the soy sauce with the mushroom soup and boullion, then pour over mixture in pot. Set on low 6-8 hrs. Serve with rice or chow mein noodles.