Preheat the oven to 180C/350F/Gas Mark 3 and lightly grease a baking sheet and line with some greaseproof paper.
In a large mixing bowl, beat the butter until creamy.
Then add the icing sugar and beat until light and soft.
Sift the corn flour into the same bowl along with the flour and cocoa powder and mix until the mixture comes together – it should be dough like.
Bring the dough together with your hands and divide it into 24 equal parts – it’s actually easiest to do this by shaping the dough into a sausage shape and cutting into half, then quarters, then eights etc. They will be about the size of a brussel sprout.
Roll the pieces of dough into balls and place them a little apart on the baking sheet tray. Using a eating fork, flatten each biscuit lightly.
Bake in the preheated oven for around 10-12 minutes – they should be firm.
Remove from the oven and allow the biscuits to cool on the tray for 5 minutes before transferring to a wire rack to cool fully.
When cool, spread a good layer of chocolate spread on the flat size of one biscuit and sandwich another biscuit on top – make sure the flat side of both biscuits are toughing the chocolate spread to give a more rounded cookie finish.