Melt butter in a large skillet with rosemary and sauté for 2 minutes. Add squash, salt and cider. You may need to add some additional cider (or water), enough to cover the squash. Bring to a boil and braise for 20 minutes or until tender. At this point the juice should be reduced to a glaze. If not, raise heat for a few minutes until excess liquid evaporates. Add freshly ground black pepper to taste.