Traditional Scottish Petticoat Tails Shortbread

Cream butter and caster sugar together until pale.

Stir in flour and ground rice (or cornflour) to make a stiff dough.

Roll into a large circle about 1cm thick on a baking sheet.

Crimp the edges with a thumb or fork to look like a 16th-century petticoat.

Score into 8 equal triangles and prick with a fork.

Bake at 150°C for 35-45 minutes until pale golden and set.

Sprinkle with sugar and cool before breaking into triangles.