For the best flavor, use fresh Key limes for the zest. If Key limes are unavailable, you can substitute with regular lime zest. Store the cooled cookies in an airtight container at room temperature to maintain their soft texture. Feel free to experiment with different types of chocolate chips or add chopped macadamia nuts for a tropical twist. For a more intense lime flavor, add 1/2 teaspoon of Key lime extract to the batter along with the vanilla extract.