Preheat the oven to 350°F. Spritz a 13 x 9 inch baking dish or similar with cooking spray.
In a stove top pan, saute onions and celery with butter until translucent. Season with salt and pepper to taste.
To a bowl add vegetables, cornbread, bread, sausage, apples, soup, beaten eggs, sage, poultry seasoning, salt and pepper. (May add Poultry seasoning 1 tsp at a time and adjust to taste)
Begin to add chicken stock to the ingredients in the bowl. Using a large spoon or spatula, fold the chicken stock through the mixture. If you use less cornbread and bread than I did, you may not need the entire 3 cans of stock. The dressing mixture should be very moist.
Pour the dressing evenly into the prepared baking dish.
Bake for 50-60 minutes or until golden.