Preheat the oven to 350 degrees F (175 degrees C).
Spread white and whole wheat bread cubes in a single layer on a large baking sheet.
Bake in the preheated oven until evenly toasted, 5 to 7 minutes. Transfer toasted bread cubes to a large bowl.
Cook sausage and onions in a large skillet over medium heat, stirring and breaking up lumps, until evenly browned, 6 to 8 minutes. Add celery, sage, rosemary, and thyme; cook and stir until flavors blend, about 2 minutes.
Pour sausage mixture over bread in bowl. Mix in chopped apple, dried cranberries, parsley, and liver. Drizzle with turkey stock and melted butter; mix lightly.
Allow stuffing to cool completely before loosely stuffing a turkey.