Butter 4 slices of bread, and place buttered side down in a cold pan. Evenly sprinkle the parmesan cheese over the bread. Then add the potatoes, and then the turkey. If you would like, feel free to add leftover gravy or cranberry sauce. Butter the remaining slices of bread and place on top. Turn the heat on to medium low, and slowly cook until browned on the bottom, then flip and cook until browned on the other side. Serve immediately.