Heat the sweet potato puree in a small saucepan, over medium heat until it simmers (some bubbles, but not boiling). Stir the potato puree while it's heating.

Stir in the chocolate (I used half semisweet and 1/2 bittersweet) until combined.

Continue stirring until the mixture is at room temperature.

Frosting will be complete when soft peaks form. This frosting doesn't get thick like a traditional frosting, but when spread on a cooled cake it hold up just fine.

Ice cake.