1.Preheat oven to 180°C (160°C fan-forced). Grease oven trays.
2.Beat butter, essence and caster sugar in small bowl with electric mixer until light and fluffy. Stir in flour, mix to a firm dough. Cover, refrigerate 30 minutes.
3.Roll dough between sheets of baking paper until 3mm thick. Cut dough into 3.5cm rounds using a cutter, place rounds about 2cm apart on trays.
4.Bake biscuits about 8 minutes or until coloured. Stand biscuits on trays 5 minutes, transfer to wire racks to cool.
5.Meanwhile, make coffee cream. Sift icing sugar into small bowl, stir in oil, essence and enough milk to make spreadable.
6.Spread biscuits with coffee cream, stand on wire racks until set. Pipe or drizzle melted chocolate over biscuits.