Scottish Shortbread Cookies

1. Sift the flour into a bowl and add the sugar. Work in the butter with your fingertips. Keep it in one piece and gradually work in the dry ingredients. Knead well.
2. Pat down on a work surface and use a rolling pin to roll the dough to about 1/2 cm (1/8 in) thickness and cut out with a cookie cutter. You will probably have to keep pushing the dough back together again, as it is very crumbly.
3. Slide the cut biscuits off the work surface with a knife and onto a baking sheet.
4. Bake in the oven at 170C (325F or Mark 3) for about 8 minutes until firm and pale golden brown.
5. Lift onto a cooling tray with a spatula and dredge with caster (superfine) sugar.