Cream butter till fluffy, add sugar gradually. Continue to cream until smooth, add salt. Gradually work in flour, kneading with your hands (do not use mixer), until well blended.
Press out mixture using hands onto ungreased cookie sheet, until about 3/4" thick, into square or rectangular shape, do not allow to touch sides of pan. Cut into size about 1 to 2", prick all over with fork.
Bake at 375°F until very lightly browned, about 15-20 minutes, cool 10 minutes on sheet. Remove to paper towel and cool completely; store in sealed container or airtight wrapping.