Preheat oven to 150°C (bake (140°C fan forced). Line oven tray with baking paper.
Beat Butter and Icing Sugar until pale and fluffy.
Mix in Cornflour and Flour until the mixture comes together and forms a dough.
On a floured surface, roll dough into a log and slice into rounds, using a floured knife to prevent sticking.
Place on prepared tray chill in fridge for 20 minutes, then bake 25 - 30 minutes, until shortbread is pale but crisp.
Cool on a wire rack and store in an airtight container.