• Add the softened butter, sugar and vanilla extract to a mixing bowl and beat with an electric whisk. Crack in the egg and beat again.
• Pour the gluten free flour, cornflour and xanthan gum into the bowl and use a wooden spoon to bring the mixture together until it forms a sticky dough. Turn the dough out onto a piece of clingfilm, wrap it up and pop it in the fridge for at least 30 minutes (you can also leave it overnight at this stage or freeze it to bake later - see notes).
• Once the dough has chilled, preheat the oven to 180C / Fan 160C / Gas Mark 4. Line two large baking trays with baking paper.
• Unwrap the dough and roll it out to around 5mm thick - it can be helpful to do this between two sheets of parchment paper or plastic wrap, so it doesn't stick.
• Cut out the shapes and place them on the baking sheets with a little space between them. Scrunch up and re-roll the dough as much as necessary.
• Bake the biscuits for 10-12 minutes - they will stay quite pale. Remove from the oven and cool on the baking sheets for around 10-15 minutes until moving to a cooling rack to cool completely.

To decorate the biscuits:

• Add the icing sugar to a bowl and gradually add the milk until it forms a thick paste. Add the food colouring if using (see recipe notes). Either spoon the icing onto the cooled biscuits or use a piping bag, then decorate with edible eyes and sprinkles galore!