Preheat the oven to 350 degrees
Boil the sweet potatoes in a large pot for 15 min
Remove when tender, and strain
Mash the sweet potatoes in a large bowl
Mix in all the other ingredients, except the marshmallows
Spread the mixture in a buttered baking dish
Sprinkle the marshmallows on the top, make it a rich layer
Bake for 25-30 min until the marshmallows are golden and proud