Make the bread cubes: Preheat oven to 350 F. Place cubed bread in a single layer on a large baking sheet and bake for 10 minutes, tossing once halfway through cooking. You want the bread cubes slightly tender in the middle and hard on the edges, but not browned. Once bread has cooked remove from oven and set aside.

Heat a large skillet to medium. Add sausage and sauté until sausage is cooked through and slightly browned, about 5-7 minutes. Remove sausage from pan with a slotted spoon and set aside on a paper towel to drain.

In the same pan, add 1/2 cup of butter, the onions, apples and celery. Cook until the vegetables are softened and the onions become slightly browned on the edges, about 15-20 minutes. Add poultry seasoning and parsley and cook for one more minute. Remove form heat and season with salt and pepper to taste.

In a very large mixing bowl, gently toss vegetable mixture, bread cubes and sausage to combine. Add 3 cups of stock and fold. Continue to add about 1/4 cup stock at a time and fold, until the stuffing is moist but not soggy. Season with salt and pepper to taste.

Put stuffing into a large glass baking dish, making sure not to overfill the pan. You will have extra stuffing; put into a smaller baking dish and save for leftovers.

Dot stuffing with the remaining butter. At this point you can cover the stuffing and refrigerate for up to 24 hours or bake immediately for serving.

To bake stuffing, place in a 375 F oven for 45 minutes, until the top becomes crispy and browned.