Preheat the oven to 180°C (160°C fan) or gas mark 4 and line two baking sheets with parchment paper.

Cream together 125g of room temperature butter and 85g of icing sugar until pale and fluffy. Mix in 1 egg yolk, 1 tsp vanilla extract, and 1 tsp milk.

Sift together 175g plain flour, 1 tsp coffee powder, 50g cocoa powder, and ¼ tsp salt into the wet mixture. Stir until a soft dough forms.

Shape the dough into a disc, wrap in cling film, and refrigerate for about 15 minutes.

Roll out the dough between two sheets of parchment paper to about £1 coin thickness and cut out shapes with a bat-shaped cookie cutter.

Cut small notches at the base of each bat for stability.

Bake the biscuits in the preheated oven for about 10 minutes until sandy and aromatic.

Cool the biscuits on the sheets for 5 minutes before transferring to a wire rack to cool completely.

Melt 100g of chocolate and coat the wings and ears of the biscuits. Sprinkle with hundreds and thousands and pipe on details with icing.

Let the decorated biscuits sit until the chocolate hardens, about 15-20 minutes.