For the stuffing, place turkey in a bowl and season evenly with poultry seasoning and salt and pepper, if not included in spice blend. Add remaining ingredients and mix to combine well. Refrigerate several hours or overnight.
In a large skillet, heat a drizzle of EVOO over medium-high heat. Add sausage meat and brown and crumble with a potato masher; remove to a plate.
Add butter to the skillet and reduce heat to medium. When butter foams, add celery, apples, onions and bay leaf, and season with salt and pepper. Cook to soften, 10 minutes, then add stuffing cubes or croutons. Moisten with stock and season with poultry seasoning; combine with sausage. Grease baking dish with softened butter, fill with stuffing and dot the top of the stuffing with butter as well.