Line a baking tray with a sheet of baking parchment.
Have your little one tip the icing sugar into a large bowl. Meanwhile, measure out 4 tablespoons of cold water, then add it to the bowl, along with the peppermint flavouring.
Mix together with a spoon, and then with your hands, until you get a firm, smooth mixture. Break the mixture in half. Add a little red food colouring to one piece and leave the other one white (or you might like to make other colours).
Dust a little of the extra icing sugar over the table, then let your children knead a piece each until the colour is nice and even.
Sprinkle some more icing sugar over rolling pins then roll each piece out until it is a little bit thicker than a pound coin – it may be easier for smaller children to roll a small piece at a time. Cut out shapes using small Christmas-themed cutters.
Your children can then lift the shapes off the table with a spatula and move them to the baking tray. Let them decorate with writing icing, sprinkles and cake decorations. Leave to dry for at least 4 hours or overnight.