Another classic Christmas cookie - Shortbread is a traditional Scottish dessert that consists of three basic ingredients: flour, sugar, and butter. According to Wikpedia, this cookie resulted from medieval biscuit bread, which was a twice baked, enriched bread roll dusted with sugar and spices and hardened into a soft and sweetened biscuit called a Rusk.
Eventually, yeast from the original Rusk recipe was replaced by butter, which was becoming more of a staple in the British Isles. Despite the fact that shortbread was prepared during much of the 12th century, the refinement of shortbread was actually accredited to Mary, Queen of Scots, in the 16th century.
The name of one of the most famous and most traditional forms of shortbread, petticoat tails, were named by Queen Mary. This type of shortbread was baked, cut into triangular wedges as they are in this recipe from Cook’s Illustrated.