Pre-heat your oven to 180°c (160°c for fan-assisted ovens or Gas Mark 3) and grease a couple of baking trays with a little butter.
In a large bowl, cream together the butter and caster sugar until it becomes light and fluffy. Add the orange zest, orange extract & chocolate chips and mix until combined.
Sift in the flour and cornflour and mix to form a stiff dough, using your hands if necessary. Tip the dough onto a lightly floured worktop and gently knead until smooth.
Roll your dough to around 1cm thick and cut unto your desired shapes. Transfer each shortbread to your pre-greased baking trays and prick the tops with a fork.
Bake in your pre-heated oven for 15-20 minutes until the edges of the shortbread are golden.
Remove from the oven and sprinkle a little sugar over each shortbread. Leave to cool on tray for around 10 minutes before transferring to a wire rack to cool completely.