Pre-heat the oven to 200°C/180°C fan/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 thoroughly cool.
Add the almond milk to the blender. Scoop out the sweet potato flesh and add to the blender along with all the other ingredients. Whizz until smooth. 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.