Make the pesto by combining all of the ingredients in a food processor. Mix until smooth, scraping down the sides as needed.
Mix with the diced chicken and celery, if using, to get everything well coated. You probably won't need all of the pesto - just add it until you like the mix. Extra pesto is great on bread, as a sandwich spread or on a spoon.
Enjoy immediately or let it sit in the fridge for a few hours. It gets more and more delicious. Enjoy!
Notes
Chicken: The chicken for this recipe needs to be cooked and cooled, so please plan accordingly. You can roast it, boil it or use a rotisserie chicken from the store.Greek yogurt: I use all Greek yogurt (nonfat or 2% are fine) but you could substitute in some mayonnaise if you prefer.Nuts: Most pesto calls for pine nuts, but I find walnuts work great as well. Plus they are much cheaper and last longer! Use whichever you prefer.Serving Ideas: Serve as a sandwich, wrap, as a salad, with crackers, with veggies or in mini phyllo or wanton cups.Storing: Store in a covered container in the fridge for up to 4-5 days.