3 large sweet potatoes, cooked until tender, or 1 29-oz. can of sweet potatoes
1 egg
1/3 cup sugar
1/2 tsp. cinnamon
1 tsp. vanilla extract
2 cups mini marshmallows

Heat the oven to 350 degrees. Combine the sweet potatoes, egg, sugar, cinnamon, and vanilla extract in a bowl and mix with an electric mixer on medium speed for 2 to 3 minutes. Empty the mixture into a 2-quart ungreased baking dish. Bake uncovered for 25 minutes. Top with the marshmallows and bake for an additional 5 minutes. Serves 4 to 6

Source:

http://familyfun.go.com/thanksgiving/thanksgiving-dinner-recipes/thanksgiving-appetizers/2/