Lots of Butter, Little Moisture

• The "short" in shortbread refers to the cookie's texture. Shortbread has a high ratio of butter to flour compared to other sweets. The cookies also have little moisture, a factor that slows the development of gluten in the dough. These conditions result in cookies that are crumbly and tender – a quality that bakers call "short."

Cornstarch Alters Texture

• Cornstarch has become an essential ingredient for cooks who want their shortbread to have a silkier texture and a more delicate flavor. Typically cornstarch can replace up to one quarter the amount of flour in a shortbread recipe to produce dough that can be used in traditional molds. Shortbread often is formed in a round mold that imprints a Scottish thistle on the top. The dough is chilled to help it set, then removed from the mold before baking on a flat cookie sheet.

A Sand-Like Mixture

• While most shortbread recipes using cornstarch limit the amount to a quarter of the amount of flour, there are also versions in which the cornstarch is increased to equal half the amount of the flour. That much cornstarch produces a sand-like mixture instead of more flexible dough. Shortbread with a high amount of cornstarch often must be worked by hand instead of a mixer. In addition, a high-cornstarch recipe won't mold. It can only be spread on a flat cookie sheet, scored into "fingers" using a knife and pierced with a fork to release moisture. The cookies are then cut out completely after cooling.

Additions Spice It Up

• Besides substituting cornstarch for some of the flour, contemporary shortbread recipes may add flavor extracts, spices, crushed nuts, chocolate, citrus zest or dried fruits. No matter how much cornstarch is used, the quality of shortbread cookies depends entirely upon the quality of the ingredients. Making shortbread isn't the time to skimp, particularly on the butter. Shortbread must bake slowly in a low oven, usually between 300 and 325 degrees Fahrenheit. Baking shortbread until it's just done produces a tender, crumbly cookie; baking for another five to 10 minutes creates a cookie with snap.