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 cooker. (It may be necessary to stack squash halves in cooker so they fit, but they still will cook evenly.)
In small bowl, mix remaining ingredients; spoon into squash.
Cover; cook on High heat setting 3 to 4 hours.