Traditional Scottish Shortbread for Christmas

In our family it isn't Christmas without some of our traditional recipes that we have made each year without fail.  One of my favourites is the original Scottish shortbread cookies made with only 3 ingredients, butter, white sugar and white flour!!  Cream one pound of softened butter with one cup of white sugar. Add five cups of white flour, one cup at a time.  Knead well into six inch logs, flattened into squares with a knife.  Slice in half inch slices and prick with a fork.  Bake on an ungreased cookie sheet for 35 minutes in a slow 275 degree oven until light browned,  Store in a tin ( the longer they sit, the better they taste) Enjoy!!!!!