Preheat the oven to 375. Spray the baking dish with non stick baking spray.
Wash and cut your onion, celery and Brussel Sprouts.
Over medium heat, add the oil, onions and garlic into a sauté pan and cook them until golden.
Transfer the cooked onions to the casserole dish.
In the sauté pan brown your ground turkey than drain it and add to your casserole dish on top of the onions.
Add the Brussel Sprouts and celery to the dish on top of the ground turkey.
In a bowl, mix the gravy mix and the water together, stir in the stuffing mix. Pour the stuffing mix on top of the other ingredients in the casserole dish.
Mix everything together so that all of the ingredients are mixed well.