Cook pasta shells according to package directions, drain and set aside.
In a large skillet, brown turkey with onion until turkey is cooked through and onion is tender. Stir in salt, italian seasoning and garlic powder and cook for 1 minute. Stir in ½ of the sauce, ricotta cheese, and parmesan cheese.
Fill a gallon sized ziplock bag with half of the meat mixture and snip a corner off of the bag. Squeeze the filling into the pasta shells, arranging them in a 9x13" baking dish as you. Refill bag when needed and continue until all the filling is used.
Pour remaining sauce over the stuffed shells and top with mozzarella cheese. Cover with foil and bake 30-40 minutes or until hot and bubbly.