Melt the chocolate in a heatproof bowl over a pan of barely simmering water. Once melted, turn off the heat and leave the chocolate in the bowl to keep warm while you assemble the spiders.
Unroll some of the liquorice wheels and cut into 2-3cm lengths to use as the Chocolate spiders’ legs.
Splodge a small tsp of chocolate onto half of the cookies. Arrange eight liquorice legs on top, then sandwich with another cookie. Spread some more chocolate on top of the second cookie to cover, then put somewhere cool to set.
Use the icing pens to add eyes, by first blobbing two big dots of white icing on each, topped with two smaller dots of black icing.