PREHEAT oven to 325°F Place sweet potatoes on microwaveable plate. Microwave on HIGH 8 minute Turn potatoes over; continue microwaving 9 to 10 minute or until very tender. Let stand 5 minute Cut potatoes in half lengthwise. Scoop pulp into large bowl; discard skins.
ADD cream cheese, brown sugar, cinnamon and nutmeg to potato pulp. Mash with potato masher to desired consistency. Spoon into 9-inch square glass baking dish.
MIX cereal and butter in medium bowl until well blended. Stir in marshmallows. Sprinkle evenly over potato mixture.
BAKE 30 to 35 minute or until topping is golden brown and mixture is heated through.
Mashed potato mixture can be prepared ahead of time. Cover and refrigerate up to 2 days. When ready to serve, uncover, sprinkle with streusel topping and bake as directed.