Butter vs. Margarine

• Most butters sold in the U.S. average about 80 percent milk fat, with the remaining 20 percent including water and flavorful milk solids. Stick margarine is similar, using plant-derived fats for most of their volume and complementing them with water, salt and usually milk solids to provide a buttery flavor. Both butter and margarine are available in "light" versions that have extra water beaten in, bringing their fat content to 60 percent or lower. These are intended for table use, and don't perform well for cookie-making. The extra water tends to alter your recipe's balance, leaving the cookies chewy, rather than crisp.

Melting In the Heat

• One of the most important differences between butter and margarine, from the baker's perspective, is their melting temperatures. Butter melts at just above 90 degrees Fahrenheit, while margarine -- depending on the brand and its formulation -- melts at temperatures in the high 90s. This means cookies made with butter tend to spread more and have a crisper texture, while cookies made with margarine spread less. Most sugar cookies are rolled and cut, so switching to margarine will result in cleaner-looking edges and sharper shapes. That's an advantage, especially if you cut the cookies into shapes. If bake sugar cookies in drop-cookie or icebox cookie form, they won't spread as well when you use margarine.

A Matter of Taste

• Either butter or margarine can hold the advantage in texture, depending on your desired result, but when it comes to flavor, there's no contest. Sugar cookies made with butter taste better, hands down. Margarine's lower cost makes it a good option when you're making lots of cookies, and unlike vegetable-oil shortening, it still gives the cookies a modestly buttery flavor. You can compensate for the flavor difference by using a high-quality vanilla extract in the cookies, or by icing them or drizzling them with chocolate.

The Health Question

• Butter's high levels of saturated fat and cholesterol pose a problem for health-conscious cookie lovers. Both are thought to play a role in cardiovascular health, so if cookies are your guilty pleasure, switching from butter to margarine would seem to ease that guilt. Unfortunately most margarines include partially hydrogenated vegetable oils, which contain substances called trans fats. Trans fats are now thought to be equally hazardous, which complicates the picture. If heart health is your key concern, look for a brand of margarine that specifically states it contains no trans fats.