In a small bowl, combine brown sugar and spice; spoon into squash halves.

Sprinkle with raisins; dot with butter.

Wrap each squash half individually in heavy-duty aluminum foil; seal tightly.

Pour water into slow cooker.

Place squash, cut side up, in slow cooker (packets may be stacked).

Cover and cook on high setting for 4 hours, until squash is tender.

Open foil packets carefully to allow steam to escape.