Escarole's firm-textured green leaves hold up well during cooking. Uncooked, they make a hearty contribution in salads, too.
Prepare the soup, excet the escarole, and freeze in a 2-quart container. Be sure to leave an inch or so of headroom at the top of the container to allow for expansion. Reheat the soup in the microwave or on the stovetop and add the escarole just before serving.