Remove the skin and any bones from the fish. Cut into 2-inch squares. Add to the bowl of a stand mixer. Add the cream cheese, Gouda, lemon juice/zest, horseradish, sour cream, and spices. Using the paddle attachment, on low, slowly mix together the ingredients until a fairly uniform mixture forms.
Place the watercress in a shallow bowl.
If the mixture isn’t too soft (mine wasn’t), mold into a ball and roll in the watercress. Press the watercress into the sides of the ball and shape. If your mixture is very soft, refrigerate for about 30 minutes before rolling in the watercress.
Serve immediately or refrigerate up to 24 hrs. I’ve had good luck refrigerating it with the watercress already in place but you can wait to do that step until it is ready to serve. Allow to sit at room temperature about 10 minutes prior to serving.