Prep the chicken: If using rotisserie chicken, remove the skin and bones, then chop or shred into bite-size pieces. You want about 3 cups total.
Make the dressing: In a large bowl, whisk together mayonnaise, sour cream, Parmesan, garlic, lemon juice, Dijon, onion powder, smoked paprika, and olive oil if using.
Season with a pinch of salt and pepper.
Taste the base: Before adding the chicken, taste the dressing. It should be garlicky and bright with a little tang. Adjust salt, pepper, or lemon as needed.
Add the mix-ins: Stir in celery, red onion, and parsley.
Mix until everything is coated but still crisp.
Fold in the chicken: Add chicken and gently toss until well combined. Don’t overmix—keep the texture intact.
Chill for best flavor: Cover and refrigerate for at least 30 minutes. This allows the garlic and Parmesan to meld.
Serve: Spoon into lettuce wraps, over a bed of greens, or alongside cucumber slices.
Finish with a crack of pepper and a sprinkle of Parmesan if you like.