Cream butter and sugar well. Work in flour and salt. Knead well. Divide into two rounds, flatten each, and cut into diamond shapes or use small cookie cutter. ( Chill dough before cutting ) Put on ungreased cookie sheet, 3 cm apart. Bake 30 to 45 minutes at 250 degrees. After 30 minutes, check to see if done. Check frequently. Do not let tops brown. This has long been a favorite Christmas cookie treat! ----