Ingredients
120g butter, softened
120g caster sugar
2 tbsps golden syrup
3 tbsps double cream
60g cocoa powder
180g plain flour
40g cornflour
½ tsp bicarbonate of soda

Ingredients for the filling
50g butter
100g icing sugar
1 tbsp cocoa powder
1 tbsp double cream

Method
For the biscuits, put the butter and sugar into a stand mixer and cream on medium with the paddle attachment until light and fluffy, around  1-2 minutes. Add the cream and golden syrup and mix briefly until incorporated.  Add the cocoa powder, plain and corn flours and bicarb and mix on a low speed until you have what looks like breadcrumbs.  This will likely take around 3 minutes.

Stop the mixer and with your hands, push together the mixture and it will eventually come together so keep going until you have a dough. No additional liquid should be needed but if the dough really is not coming together then add ½ tbsp of cream.

Shape into a ball, cover with cling film and put into the fridge for 1 hour.

Preheat the oven to 180c.

Roll out the dough between two sheets of greaseproof paper to the thickness of a £1 coin.  Take off one sheet of greaseproof and then cut into fingers.  I like mine to be long like the originals and find a ruler is the perfect width for this and I like the length to be 6cms.

Transfer each finger onto a baking tray, leaving some space between them and cook for 10-12 minutes.  Chocolate biscuits are more difficult to tell when they are done so be careful, the biscuits should be set feeling albeit softish.  You do not want to overbake them or they will taste burnt.  Leave to cool for at least an hour.

When the biscuits are cool make the filling by beating together all of the ingredients.

Lightly spread the filling over half of the biscuits and top with the plain biscuit to make a biscuit sandwich.