01 - Roast or steam the sweet potato until very soft; let it cool, peel, and cut into chunks.
02 - In a blender, combine sweet potato, milk, honey or maple syrup (if using), and vanilla extract. Blend until completely smooth.
03 - Pour the mixture into a saucepan and heat gently over medium-low heat until steaming hot, stirring occasionally (do not boil).
04 - Pour the latte into mugs. Sprinkle with cinnamon or nutmeg if desired. Serve hot.