Place sweet potatoes in a large saucepan and cover with water. Bring to a boil. Reduce heat; cover and simmer for 10 minutes or until tender. Drain potatoes and place in large bowl; mash. Add marshmallow crème and butter; beat until smooth. Add the milk, eggs and extracts; mix well.
Combine the sugars, flour, cinnamon and nutmeg; gradually beat into potato mixture until well blended. Pour into pastry shell.
Bake at 350 degrees for 45-50 minutes or until a knife inserted near the center comes out clean. Cool on a wire rack. Serve with whipped topping. Refrigerate leftovers.