Cream butter and sugar until light and fluffy. Add sifted flour and cornstarch, and salt. Mix well. Turn out onto lightly floured board, knead lightly. Divide in half, shape into 2 rolls 4 cm wide, 15 cm long. Wrap in plastic wrap, refrigerate 1 hr or until firm. Cut into 1 cm slices. Place on oven trays. Bake 180ºC , 10-15 mins or until cooked. ----