One of the most common questions facing any cook or baker is how to substitute for a missing or unavailable ingredient. Some substitutions are easy, others can be quite difficult. In the case of cookie making, substituting one fat for another is not usually troublesome. Depending on the substitute you choose, you may not need to adjust the recipe much at all.
What Shortening Does
The shortening in sugar cookies works together with the sugar to create a light, crispy texture. As the sugar is creamed into the shortening, the corners of the sugar crystals leave small gouges in the room-temperature fat. Over a period of a few minutes, the creaming process creates tens of thousands of tiny air pockets in the fat. When the cookies are baked, the baking powder or baking soda in the recipe will create small amounts of carbon dioxide, which will seep into these small air pockets and expand them, making the cookies light and crisp.
Butter can be substituted for the shortening in most cookie recipes. Butter will improve the flavor of most cookies, but can be more difficult to work with than shortening. If you live in a warm climate, butter will tend to soften and produce cookies that spread too much. This can be prevented by chilling the dough before putting it on the cookie sheets. Butter also contains a percentage of water, while shortening is pure fat. This will not matter except in large-volume recipes, where the flour might need to be increased slightly.
Margarine is very similar to shortening in its makeup, since both are manufactured from vegetable oils. Simply replace the shortening with an equivalent quantity of margarine, and the recipe will need no further adjustment. Be sure when purchasing margarine for baking that you do not select a soft, spreadable margarine, which is high in water content and unsuitable for baking. It is best to choose a non-hydrogenated margarine that is trans-fat free, to avoid any health problems.
Highly refined lard can be used in place of shortening in many cookie recipes, though some brands will leave a faint hint of pork in the flavor. Some manufacturers produce a butter/margarine blend in varying proportions, which also works well for baking. Coconut oil can be purchased in solid form similar to shortening under the name copha, though it is hard to find in the United States. A less common alternative, still popular in some Amish and Mennonite communities, is to use purified chicken fat for light, crisp cookies.