Preheat oven to 400 degrees.
Peel and boil the sweet potatoes and garlic in water until soft. Drain the potatoes.
Once the sweet potattoes are done add the chicken broth, milk, sour cream, salt and pepper and mash.
While cooking the sweet potatoes, In a large sauté pan brown the turkey. Once the turkey is cooked, set aside on a plate lined with paper towels.
Add the olive oil to the pan, then add the onion and celery. Season with salt and pepper.
Cook for about 12 minutes, until celery is soft. Add the garlic and mushrooms, sauté for another 3-4 minutes.
Add the flour, salt and pepper and mix well.
Add in the frozen vegetables, chicken broth, tomato paste, Worcestershire sauce, rosemary, cooked turkey, and mix well.
Simmer on low for about 5-10 minutes.
Spay the baking sheet with non stick spray. Put the turkey and veggies mixture into the pan and spread evenly.
Top the meat and veggies mixture with the mashed sweet potatoes.
Bake for 20 minutes or until potatoes turns golden. Remove from oven and let it cool 10 minutes before serving.