Scotch Shortbread

1 lb. butter ( 2 cups) , at room temperature
1 cup confectioners' sugar
4 cups flour, scooped and leveled
1/3 cup cornstarch

In large bowl cream butter and gradually add sugar, creaming well. Add flour and cornstarch (which have been sifted together) a little at a time, creaming until all is blended. Gather into a ball; knead with warm hands on lightly floured board 5 - 10 minutes. With rolling pin, roll out to 1/2 inch thick. Cut into 1 1/2 inch squares; prick top with fork tines;bake on ungreased cookie sheet 25 to 30 minutes or until barely browning.
If you roll to 1/4 inch thickness and cut with smaller shapes bake only 9-11 minutes.
Remove and allow to cool. Store in foil-lined tighly covered tin. May be eated at once, but ripens and mellows with age. Keeps months.
Melt dipping chocolate and dip half the cookies in chocolate to make them extra special.