Cut squash into halves or fourths; remove seeds and fibers. Place cut sides down in microwavable dish. Cover with plastic wrap, folding back one edge or corner 1/4 inch to vent steam. Microwave on High 13 to 15 minutes or until tender when pierced with fork. Let stand 5 minutes. Scoop flesh from shells and mash with fork.
Heat oven to 350°. Butter 1 1/2-quart shallow au gratin dish or casserole. Mix squash, cranberries, brown sugar, whipping cream and salt in medium bowl. Spoon into au gratin dish.
Spread butter on bread. Tear buttered bread into pieces. Place bread, cheese and nutmeg in food processor. Cover and process until fine crumbs form. Sprinkle over squash mixture.
Bake uncovered 25 to 30 minutes or until thoroughly heated and crumb topping is brown and crisp.