Combine the first 6 ingredients in a large saucepan; bring to a boil, and cook 20 minutes or until the sweet potato is very tender. Strain the mixture through a colander into a bowl, reserving 1/2 cup liquid. Discard cinnamon stick.
Place sweet potato mixture, reserved 1/2 cup liquid, maple syrup, ginger, and nutmeg in a food processor, and process until smooth.
