Prepare the chicken by shredding or dicing it into bite-sized pieces. If using raw chicken, cook it thoroughly until it reaches an internal temperature of 165°F (75°C).
In a large mixing bowl, combine the prepared chicken, finely chopped celery, dried cranberries, and chopped walnuts. Stir gently to mix.
In a separate bowl, whisk together the mayonnaise, Dijon mustard, apple cider vinegar, salt, black pepper, garlic powder, and onion powder until smooth.
Pour the dressing over the chicken mixture and stir until well coated. If using fresh parsley, fold it in. Cover and refrigerate for at least 30 minutes.