Preheat the oven to 160c fan.
In a bowl, add the flour and sugar and stir. Add the chilled butter cubes to the dry mixture and work together with your fingers until it looks like breadcrumbs.
Add the orange zest and with your hands, bring together to form a dough.
Form the dough into a disc, wrap in clingfilm and chill in the fridge for 1 hour.
Roll the dough out in between two pieces of greaseproof paper with a little dusting of flour.
Cut out 24 squares, you will need to gather the excess dough, bring together and re-roll.
Place the squares onto two lined baking sheets. Cut a shape out of 12 of the biscuits.
Bake in the oven for 8 minutes.
Leave to cool on a wire rack. The biscuits will be very soft, but will firm up once completely cooled.
Once cooled, spread or pipe marmalade onto the 12 full biscuits and use the others to sandwich them gently together.
