Chocolate and sweet potato batters are swirled together to make this moist, tender spice cake from Patricia Polley of Columbus, Ohio. Wrap and store the cooled cake overnight for easier slicing. (It's a great alternative to coffee cake for brunches.)
For 2 cups mashed, plain sweet potatoes, peel 1 pound sweet potatoes. Cut into 2- to 3-inch pieces. Cook potato pieces, covered, in enough boiling water to cover for 20 to 25 minutes or until potatoes are tender. Drain well. Mash with a potato masher or beat with an electric mixer until smooth.