Cook the pasta according to the package instructions, then drain and rinse with cold water.
In a large bowl, combine the cooked chicken, diced apples, chopped celery, walnuts, and dried cranberries.
In a separate bowl, mix the mayonnaise, Dijon mustard, lemon juice, salt, and pepper until well combined.
Pour the dressing over the chicken mixture and stir until everything is coated evenly.
Taste and adjust seasoning if necessary, adding more salt, pepper, or lemon juice as desired.
Chill the salad in the refrigerator for at least 30 minutes to allow flavors to meld.
Serve the salad on a bed of greens or in a bowl, garnishing with extra walnuts or cranberries if desired.