Cranberry Sausage and Apple Dressing

1 stick unsalted butter
1 large onion , chopped 
4 celery ribs with leaves, chopped
10 cups cubed stuffing bread or firm white  bread, cut into 1/2-inch cubes  and dried overnight in the oven
1/4 cup chopped fresh flat_leaf_parsley
3 cups turkey stock or chicken_broth
2 tsp poultry_seasoning or to taste
1/4 tsp dried thyme
1/2 tsp fresh ground black_pepper
1 tsp onion_powder
1/2 tsp salt
1 pound bulk turkey breakfast sausage
1cup dried cranberries
2 large granny smith apples, cored and diced