Directions

1. Heat oven to 200C/180C fan/gas 6 and line a baking sheet with baking parchment.
2. Put the butter in a bowl and beat with electric beaters until soft and creamy. Beat in the sugar, then the egg and vanilla, and finally the flour to make a dough. If the dough feels a bit sticky add a little more flour and knead it in. Wrap in cling film and put in the fridge for half an hour.
3. Heavily flour a surface and cut the pastry in half. Roll out one half to 5mm thickness. Using a cookie cutter in the shape of a ghost (or any spooky shaped cutter you like), cut out 12 ghost shapes, which will make 4 cookies. Put the cut shapes on a baking tray lined with baking paper and put back in the fridge. Repeat with the second half of the pastry. Swap into the fridge, taking the chilled ghost biscuits out.
4. Using a smaller cutter or a knife, cut a ghost-shaped hole in the middle of 4 of the biscuits on the tray, this is the space to store the surprise centre! Put these biscuits into the oven to bake for 10-12 mins, until pale but cooked through. Transfer to a wire rack to cool. Repeat with the other tray.
5. Once all the biscuits have cooled completely, they are ready to be assembled. Mix the icing sugar with 3 tbsp of water and mix well. It should be quite thick so add a little more icing sugar if the mixture is too runny. Take a biscuit without the centre missing, and spread or pipe a little icing around the edge. Press a biscuit with a centre missing on top, then sprinkle silver balls into the pocket that you have created (or rainbow sprinkles as an alternative, if you're serving to very young children). Spread icing on the edge of the second biscuit and press another whole biscuit on top. Set aside to firm up. Make sure you leave them for a while so they don't slide when you are finishing the decoration.
6. Once the biscuits feel firm and the icing has set, use the sugar paste to decorate them as you please, rolling it out, cutting it to shape and topping the biscuits. You may have to use a little of the icing to glue it down. Decorate with icing pens if you like.