Let a friendly bat perch on your glass of milk or cuppa this Halloween with these spooky biscuits – add vanilla buttercream for bourbons. 1. Heat oven to 180C/160C fan/gas 4 and line two baking sheets with baking parchment. Beat the butter and sugar together until creamy and pale, then beat in the yolk, the vanilla and milk. Sift the flour, coffee, cocoa and salt into the bowl, then mix together to make a soft dough. Shape the dough into a disc, wrap and chill for 15 mins. 2.