01 - Roast or steam the Korean sweet potato until completely tender throughout, approximately 20-25 minutes. Allow to cool until safe to handle, remove the skin, and cut into 1-inch pieces.
02 - Combine the prepared sweet potato chunks, milk, sweetener (if using), and vanilla extract in a blender. Process on high speed until completely smooth and creamy, approximately 45-60 seconds.
03 - Transfer the blended mixture to a small saucepan. Warm over medium-low heat, stirring frequently, until steaming hot but not boiling. Pour immediately into preheated mugs.
04 - Sprinkle the surface generously with ground cinnamon or freshly grated nutmeg. Serve immediately while hot and enjoy this comforting Korean beverage.