Cut squash in half crosswise; remove seeds and membranes.
Pour water into 5- to 6-quart slow cooker. Place squash halves, cut sides up, in slow cooker. If necessary, stack squash halves in slow cooker so they fit. In small bowl, combine all remaining ingredients; mix well. Spoon into squash halves.
Cover; cook on high setting for 3 to 4 hours.