I use diced carrots, onions, celery... saute them first in some butter till the onions are translucent. You can add peas, green beans, corn, whatever your family likes. I make a "gravy" for it with chicken broth, poultry seasoning or sage, thicken with flour or corn starch. put all that in your casserole dish, add the turkey (I guess you're using leftover cooked turkey?), then top with the mashed potatoes. Brush a bit of melted butter or margarine (or use butter flavored cooking spray for less fat) over the top of the potatoes. Bake for ~ an hour at 350F. Let it stand 10 minutes, then serve. Good luck, let us know what you end up doing and how it turns out!