Place the spinach in a mesh strainer; run under warm water until the spinach is defrosted. Squeeze the excess liquid from the spinach until dry.
Combine yogurt, cream cheese, water chestnuts, salt, onion powder, garlic powder, and parsley in the bowl of a food processor. Process 30 seconds, scrape down the sides, then process an additional 30-60 seconds until smooth.
Transfer the mixture to a mixing bowl. Add the spinach and mix with a rubber spatula until combined.
Place in the refrigerator and chill for at least 1 hour.
Serve with pita or your favorite sliced raw vegetables.
Notes
Bagged frozen spinach defrosts more quickly than boxed spinach, but feel free to use what you have!
Full-fat greek yogurt will yield the best flavor.
Store the dip in a tightly sealed container in the fridge for up to a week.