THE HOLIDAY season often means mouth-water- ing, once-a-year festive treats. Rich, buttery shortbread is savored throughout the year, but still holds a time-honored place among the specialties traditionally served during the Yuletide season. Shortbread has its roots in Scotland as an integral part of the traditional .Christmas and Hogmanay (also known as New Year’s Eve) meals. The classic large, round short- bread biscuit is derived from the ancient. Yule bannock, a Christmas. oatcake, which was notched’ around the edges to signify the sun’s rays. Three basic ingredients — flour, butter and sugar — work together to, create the’ melt-in-your-mouth goodness -of shortbread. Short- bread jis rich and firm, yet tender. It’s the very ‘‘short’’ texture that _ gives it the name shortbread. ‘Shortbread: made in’ Scotland boasts many different local ver- sions of the basic mixture. . In Edinburgh, it is decorated . With slivers.of peel and almonds, .- while: in” Ayrshire ‘it -is . enriched “with “cream ‘and eggs. In. the Shetland . and Orkney Islands, «shortbread contains caraway. seeds ” and is known as bride’s bonn, . Today, shortbread is enjoyed in its basic form as well as enhanced -