{from Simply Recipes} 

3 vanilla beans

1 cup vodka

glass jar with tight fitting lid

1. Use kitchen scissors or a sharp paring knife to cut lengthwise down each vanilla bean, splitting them in half, leaving an inch at the end connected.
2. Put vanilla beans in a glass jar or bottle with a tight fitting lid (mason jars work well). Cover completely with the vodka.
3. Give the bottle a good shake every once in a while. Store in a dark, cool place for 2 months or longer.

Kitchen Notes:
Commercial vanilla extract usually has simple syrup (sugar water) added to the extract to give it a sweet aftertaste. You can do this if you want, but if you are using the vanilla for baking, there really is no need.
Lasts for years. You can keep topping it off with vodka once in a while as you use it, just remember to give it a good shake.
You can also make vanilla sugar by putting a split vanilla bean into a jar of white, granulated sugar. Great way to infuse the sugar with vanilla flavor for baking.