POTATOES.......Preheat oven to 350. Bake or boil sweet potatoes until soft. Cool, peel and mash. Combine potatoes and next seven ingredients with mixer on medium speed until smooth. Spoon mixture into greased 8x11 inch or 2 quart baking dish.
TOPPING.......Combine cornflakes and next three ingredients in a small bowl. Sprinkle over casserole. Bake at 350 for 30 minutes. Remove from oven and let stand for 10 minutes. Sprinkle marsh-mallows in rows on top; bake 10 minutes more. Let stand 10 minutes prior to serving.