In a pot on medium - high heat cook the sweet potatoes until tender about 10 minutes and drain
Add the potatoes back in the pot and add milk, cream cheese, one teaspoon of thyme, one pinch of nutmeg, and salt and pepper to taste and mash till smooth - set aside
In a saute pan on medium heat add in the olive oil, onion, celery and carrots and cook until tender about 8 minutes then add in the garlic and cook for another 2 minutes
Next add in the ground turkey, one teaspoon thyme and some salt and pepper and cook until meat is done and no longer pink.
Last add in the chicken stock, tomato sauce, ground mustard , a pinch of nutmeg, flour and Worcestershire sauce and cook for about 20 minutes until stock has reduced and mixture is thick.
In a baking dish sprayed with cooking spray add in the meat mixture and spread evenly in the dish. Next add the sweet potatoes on top and spread evenly over the meat mixture. Top with some parmesan cheese