Mix flour and sugar. Rub in butter and knead with warm hands until thoroughly combined and smooth
Divide into two equal parts and press into the bottom of lightly buttered cake tins (it should be quite thin). Flute edges with your knuckle. Pric k all over with a fork and mark each one into six sections. Sprinkle with granulated sugar.
Bake at 160C for 30 mins. When done it should just start to brown and look a little risen and spongy. Leave to cool just a little then retrace the sections right through the shortbread. turn out the sections when cold .