Scotch Shortbread
["1 1/2 c. butter (3 sticks)", "1 1/4 c. powdered sugar", "3 1/2 c. flour", "1/2 c. cornstarch"]
["Cream the butter and powdered sugar until fluffy.", "Sift the flour and cornstarch together and cut into butter mixture until coarse meal.", "Knead 1 to 2 minutes until smooth and press into cookie sheet.", "Prick with fork.", "Bake at 350\u00b0 for 45 to 60 minutes or until pale brown.", "Do not overbake.", "Cut into squares while warm."]
["butter", "powdered sugar", "flour", "cornstarch"]