Preheat the oven to 200°C/fan 180°C/gas mark 6. Scrub the unpeeled sweet potato well and pat dry. Prick several times with a fork and place on a small baking tray lined with foil. Roast for 45-50 minutes or until tender so that if it’s pierced with a knife, it slides all the way through. Remove from the oven and leave until cool.
Add the almond milk to the blender. Scoop out the sweet potato flesh and add to the blender along with the cinnamon, ginger, nutmeg, date and ice. Add more ice cubes for a frostier drink or an additional date for sweetness. Pour into a glass.
Hold a small gingerbread man-shaped cookie cutter over the smoothie and sprinkle over some ground cinnamon for a real festive treat.