1. Preheat oven to 400ºF. Grease a 9-by-13-inch baking dish. Using the shredding attachment of a food processor, shred squash. In a large bowl, toss squash with onion, garlic, nutmeg, sage, salt and pepper.
2. Spread squash mixture evenly in baking dish. Pour cream over top and dot with butter. Cover with foil and bake until tender, about 40 minutes.