Cut chicken breasts into cubes. Cook the pieces in a frying pan with water. Set aside.
In a large bowl, combine soup, tomatoes and chiles, cheese, onion, celery, corn, mushrooms, and pepper. Add Mrs. Dash seasoning to your taste. Add chicken to mix.
Spray a 13X9 Corning Ware dish with cooking spray. Layer two to three tortillas on the bottom of the pan. Add half of the vegetable/soup/chicken mix. Create another layer of tortillas. Spread the rest of the vegetable/soup/chicken mix on the top.
Bake at 350-degrees for 25-30 minutes. Let stand for five minutes and serve.