SHOW YOUR SPOTS COOKIE SANDWICHES

Steps:

• In a food processor, whizz the butter, icing sugar and vanilla until smooth. Add 1 egg and blend to combine, then tip in the flour and blitz once more. Scoop the dough into a ball and wrap in cling film. Chill for 30 mins.
• Heat oven to 200C/180C fan/gas 6. Dust 2 large baking trays with flour. Break the dough into large cherry-sized pieces. Roll into balls and put on the baking trays, spaced a little apart. Squash down the balls slightly with 3 fingers. Bake (in batches, if necessary) for 8 mins - the cookies will still be very pale at this stage.
• Remove the cookies from the oven. While still warm, quickly brush the tops with the beaten egg, then dip half in the hundreds & thousands, and press a few Smarties onto each of the remaining cookies - do this while the egg is still wet, so the toppings will stick once cooked. Bake for a further 4 mins. Leave to cool on wire racks.
• To make the icing, beat together the butter, icing sugar and vanilla. Once the cookies are completely cool, use the icing to sandwich together the 2 different cookies. Un-iced cookies can be made up to 4 days ahead and kept in an airtight container. You can fill with the icing up to 1 day ahead.