With vegetable peeler, peel squash. Remove seeds; cut squash into 1/2-inch cubes. In 1 1/2-quart microwavable casserole, place squash and cider. Cover; microwave on High 5 to 7 minutes, stirring once halfway through cooking, until squash is tender.
Stir in remaining ingredients. Cover; microwave on High 2 to 3 minutes longer, stirring once halfway through cooking, until squash and apples are very tender. Serve immediately. If desired, mash before serving.