Cook the sweet potatoes in boiling water 20 to 25 minutes or until tender
Drain and cool
Peel the potatoes and mash Combine mashed sweet potatoes frosting vanilla and cinnamon mix well Spoon into a greased 12 x 8 x 2-inch baking dish Bake uncovered at 350 for 18 minutes
Sprinkle with marshmallows Continue baking 5 minutes or until thoroughly heated