Prize Shortbread

1 cup unsalted butter
1/2 cup powdered sugar
1 egg yolk
1/4 tsp salt
Five Roses flour

Soften the butter slightly, but do not allow it to become oily. Stir in sugar, salt and egg yolk, using a wooden spoon. Add the flour, a very little at a time, until mixture is too stiff to work with the spoon.

Turn onto floured board and knead lightly, drawing in flour all the time until the lump just BEGINS TO CRACK. Divide in two.

Pat it out on 2 ungreased pie plates. Pinch edges and prick all over with a fork. Bake in a 325 to 350F oven until delicately browned. Allow the shortbread to cool on the plate.