225g unsalted butter
110g Chelsea Icing Sugar
275g plain flour
60g cornflour
Chelsea Caster Sugar, for sprinkling

Put butter in a mixing bowl and leave to soften, or heat gently in a microwave until squishy. Whisk butter with a food mixer, then blend in the icing sugar and whisk until light and white. Slowly mix in flour and cornflour.

Turn dough onto a lightly floured surface, roll out and mark with the tines of a fork. Cut into bars and transfer to trays lined with baking paper. Chill for 15 minutes.

Sprinkle with caster sugar, then bake in an oven preheated to 150°C for 15-20 minutes, alternating the position of trays during baking.

Cool on the trays for 5 minutes, then transfer to a cooling rack. Store in an airtight container.