To Make the Turkey Mixture: Preheat the oven to 350 degrees.
In a medium saucepan, combine 2 cups of the broth, the celery, onions and carrots; bring to a boil, then reduce the heat.
Cover and simmer about 5 minutes or until the veggies are tender.
In a custard cup, stir the remaining 1/4 cup of the broth and the cornstarch until smooth.
Slowly stir this into the broth-veggie mixture, then stir in the milk; cook and stir over medium heat until the mixture comes to a boil.
Reduce the heat; cook and stir for 1 minute more, then stir in the turkey, peas, parsley, sage, garlic powder, celery salt, poultry seasoning, Worcestershire sauce, drained corn, and Tony Chachere's Cajun seasoning.
Transfer the mixture to a shallow 2-quart casserole.
To Make the Pastry Crust: Lay one sheet of the phyllo dough on top of the turkey mixture.
Spray the dough with no stick spray; repeat layering and spraying the phyllo dough two more times.
Fold or crumple the edges of the dough and tuck them inside the casserole dish; bake for 35-40 minutes or until golden brown.
You can add potatoes, mixed veggies, hot pepper sauce, minced garlic to enhance the flavor.
NOTE: Even though the phyllo dough crust will get soft once you refrigerate it, it will get flaky again if you reheat it in the oven.