400• bake sweet potatoes for 1 hour. Or until soft. Let cool to touch about 20 min. Peel and mash potatoes. Lower oven to 350•beat sweet potatoes, sugar and next five ingredients together with a mixer at medium speed until smooth. Pour into a greased pan. Combine cornflakes, and next three ingredients in a small bowl sprinkle over casserole in diagonal lines two inches apart. Bake at 350• for 30 minutes. Remove from oven. Let cool for 10 minutes. Place mini marshmallows in between the rows of cornflakes. Bake at 350• for 10 minutes