Pure vanilla extract, made by macerating vanilla beans in an alcohol-water mixture, is an easy way to add vanilla flavor to baked goods, as it mixes easily into batters. (It's also a less costly alternative to vanilla beans.) Aside from being used in overtly vanilla flavored desserts, vanilla extract enhances other flavors (particularly chocolate, coffee, fruit, and nuts) and is used in all kinds of cookies, cakes, and pastries. Imitation vanilla extract is made only from artificial ingredients. While cheaper than pure vanilla extract, its flavor can be harsh.
1 tsp. extract = one 2-inch piece vanilla bean
Use vanilla beans or vanilla bean paste.
The flavor of the vanilla extract is affected by where the vanilla beans were grown. In general, Madagascar, which is what you're most likely to find, is sweet and buttery. Tahitian vanilla is known for its fragrant and floral aromas; and Mexican vanilla tastes nuttier. Many good brands are available in larger volumes at discounted rates. Always buy pure vanilla extract (it will be called that on the label), never imitation. Double-strength versions are stronger than single-strength.
The strength of the extract will dissipate with prolonged heat, so if you're adding extract to something cooked on the stovetop, such as a custard or a poaching liquid, add it after the custard or liquid is off the stove and starting to cool. If using double strength use half as much as called for unless you want a very pronounced vanilla flavor.
Because vanilla extract is sensitive to heat and light, keep the bottle in a cool, dark place; it should last for up to a year. And, if there's a bean in it, may even get stronger.