Leftover Turkey Shepherd's Pie

There I was, staring those Thanksgiving leftovers in the face. What to do with this stuff? One can only eat so many turkey sandwiches. Mashed potatoes, gravy , turkey and a few aromatics come together beautifully to make this a no brainer.

Cook's Notes- If your gravy won't thin out after you have added it to the meat and veggies in the skillet, you can thin it out with wine, stock or water. Just add a little at a time and mix it in until you get the desired consistency.
If you have leftover green beans or peas, those would also make a nice addition to the meat and gravy. Just add them to the skillet when you add the meat.

1 large onion diced
1 cup diced celery
1 cup diced carrots
3 cups turkey gravy
3 cups diced turkey meat
3 cups leftover mashed potatoes
1 cup shredded cheese
1 tablespoon olive oil
1 tablespoon butter or margarine
salt and pepper

Preheat oven to 350 degree. Spray a large casserole dish with cooking spray. In a large skillet saute the onion, celery and carrots in the butter and oil. Season the skillet contents with salt and pepper. When the onions are translucent, add the turkey meat and continue to cook for another 5 minutes. Pour the gravy over the meat and veggies. Continue to cook until the gravy heats through and is bubbly. Pour the contents of the skillet into your prepared casserole. Reheat the mashed potatoes in the microwave to make them easier to spread. Spoon the potatoes over the meat mixture and top with cheese. Bake for 35-40 minutes or until the cheese is melted and browned and the mixture is hot and bubbly.