In a large pot over medium heat, add oil and heat for 1 minute. Add celery and onion. Cook until onion is translucent about 3 to 4 minutes. Add chicken stock, parsley, thyme, salt and pepper. Bring to boil.
Meanwhile, brown sausage and chop apple.
Once stock mixture is boiling, add bread crumbs and stir well. Add browned sausage and apples and mix well.
Lightly spray 11 x 7 baking dish with olive oil cooking spray. Scoop stuffing in baking dish and spray lightly with cooking spray. Bake stuffing at 350° for 30 minutes or until top is golden brown.
If you would like your stuffing really soft, just add 1/2 cup additional chicken stock to recipe.