Preheat the oven to 350 degrees F.
In a large cast-iron skillet, combine the leftover vegetables, turkey, and stuffing. Drizzle with the gravy.
Cover with mashed potatoes and bake for 30 minutes. If you desire a crispy top, broil for 2-3 minutes before removing from the oven.
Allow to cool for 5 minutes before serving.
Serve topped with additional gravy or cranberry sauce, if desired.