Preheat the oven to 200°C / 400°F / Gas mark 6.
Line 2 baking trays with greaseproof paper, lightly greased and set aside.
Using a food processor, combine the flour, sugar, cocoa and butter and pulse until the mixture resembles breadcrumbs.
Add the egg and pulse briefly to combine.
Turn onto a lightly floured surface and gently knead to form a soft dough.
Wrap in cling film and chill for 30 minutes.
Roll out the pastry between 2 sheets of baking paper to ½ cm thick.
Cut out the bat shapes, using a cookie cutter and place on the prepared baking trays.
Bake in the oven for 8 minutes or until lightly browned.
Allow to rest in the trays for 10 minutes before placing onto a wire rack.
Ice each bat with a red writing icing pen to make eyes, or simply dot them with a toothpick using the icing.
Store in an airtight container until required.