Place the turkey on a cutting board. With a knife, split the turkey breast in half. Cut each piece horizontally without cutting completely through. Open like a book and cover the exposed surface with plastic wrap. With a mallet, flatten the meat. Remove the plastic wrap. Spread stuffing on one side of each piece. Close the other side over the stuffing. Place the stuffed turkey in a buttered baking dish. Brush the meat with about 60 ml (1/4 cup) of sauce. Cover with aluminum foil. Bake for 30 to 35 minutes.