Start by ensuring your cooked chicken is completely cold before you begin. Chop or shred the chicken into bite-sized pieces and set aside in a large mixing bowl.

In a separate large bowl, combine full-fat mayonnaise, Dijon mustard, seasoned salt, black pepper, and optional fresh dill. Stir until smooth and well blended.

Gently fold in the chopped chicken, diced celery, and sliced green onion into the dressing until everything is evenly coated.

Cover the bowl and refrigerate for at least 30 minutes to allow flavors to meld.

After chilling, give the salad a gentle stir and taste to adjust seasoning. Serve on toasted bread, in lettuce wraps, or over greens.