Mexican Chicken Casserole

1 10 3/4-ounce can condensed cream of celery soup
1 10 3/4-ounce can condensed cream of chicken soup
1 16-ounce can stewed tomatoes
1/2 cup chicken stock
Salt and pepper
2 1/2 cups corn chips
3 cups diced cooked chicken
2 medium yellow onions -- peeled and chopped
3 cups shredded sharp Cheddar cheese

Position a rack in the center of the oven and preheat to 350 degrees. In a bowl, combine the soups, tomatoes, chicken stock, and season with salt and pepper. In a casserole or baking dish, make a layer of the corn chips, then make a layer of the chicken. Pour the soup and tomato mixture over the top, and sprinkle with the onion and top with the cheese. Cover the casserole and bake for 20 minutes. Remove the cover and continue to bake for 15 minutes, or until heated through. Remove from the oven and serve.