A good recipe for Scottish shortbread cookies is the Cooking Channel's Scottish Shortbread, containing only butter, sugar, flour and salt. Another good recipe contains butter, castor sugar, flour and rice flour.
To make Scottish shortbread, whip 1 pound of softened butter and 1 cup of sugar until the mixture is light and fluffy, and then fold in 1/2 teaspoon of salt and 1 cup of sifted all-purpose flour. Gradually fold in up to 5 more cups of flour, and knead the dough by hand until the mixture turns crumbly. Press the dough onto a cookie sheet, prick it with the tines of a fork, and bake it at 350 degrees Fahrenheit for 25 minutes. Cut the cooked dough into bars before allowing the cookies to cool.
Another good recipe calls for 1 pound of butter, 8 ounces of castor sugar, 1 pound of sifted flour and 8 ounces of rice flour. After creaming together the butter and sugar in one bowl and sifting together the flours and 1 pinch of salt three times in another bowl, fold in the flour mixture into the butter mixture using a wooden spoon, and roll it into the desired shapes. Instead of using rice flour, use equal amounts of powdered sugar and castor sugar along with flour and butter.