Remove cream cheese from the fridge and let come to room temperature.
Strain the thawed spinach thoroughly! I let it thaw in a fine-mesh sieve, then use paper towels to squeeze all of the liquid out of it. You want to remove as much water as you possibly can or you’ll wind up with watery dip. A watery dip is a sad dip.
Add cream cheese, strained spinach, sour cream, Worcestershire sauce, minced shallot, chopped water chestnuts, garlic powder, salt, and cayenne pepper (optional) to a large bowl and stir until well combined.
Taste and adjust seasonings. You may want to add a little more salt or garlic powder to suit your tastes.
Refrigerate until ready to serve. I recommend preparing at least 4 hours in advance so the flavors have time to meld.