Boil water and cook pasta for 9 minutes. Drain and set aside.
In a saucepan, heat 1/4 cup of water. Add onions and sautee gently for 10 minutes, stirring frequently and adding more water as needed. Add celery; keep cooking. Add mushrooms at the end and cook until all are fork-tender.
Dice the cooked turkey.
In a large bowl, mix pasta, drained vegetables, turkey, soup, milk, soy sauce and Parmesan cheese. Stir; pour into casserole dish.
Sprinkle shredded mozarella on top.
Cover casserole dish and bake, covered, at 350 degrees for 45 minutes.
Let cool 5 minutes before serving.