For "single-fold" vanilla extract(this is the extract you find in most stores) Use .8 ounces (or 22 grams) of vanilla beans per 1 cup of vodka (or other 80 proof alcohol)
For "double-fold" vanilla extract(much stronger flavor preferred by most professional bakers) Use 1.6 ounces (or 44 grams) of vanilla beans per 1 cup of vodka (or other 80 proof alcohol)
Cut the vanilla beans in half lengthwise and scrape out the vanilla flecks inside. Add the flecks and the beans to the vodka in a glass jar with a fitted lid. Make sure the vanilla beans are submerged under the alcohol otherwise any exposed parts can become slimy and potentially ruin your extract. Place the extract in a dark, cool place, shaking occasionally for the first few weeks. The extract "can" be used in as little as 8 weeks but it won't have reached optimal potency. The extract gets better with age. For far better results use after 6 months and for optimal results wait 12 months.
Once the extract is ready, place the funnel on the glass jars and fill them with the extract. If you like, to get even more flavor out of the beans as the extract ages, slice the used vanilla beans to fit the length of the jars and place about 2 pieces in the 2-ounce jars and 4 pieces in the 4-ounce jars. That way the extract will continue to "ripen" as it sits.Makes 1 cup or 8 ounces of premium vanilla extract*See blog post about how to reuse vanilla beans
One of the most important factors that determines the quality of the outcome is how long you allow the vanilla extract to age. BE PATIENT. While you "can" use it in as little as 8 weeks the flavor becomes vastly superior the longer it ages. For better results wait 6 months, for best results wait a year. I make a large batch every year to use the following year, that way I always have 12-month aged vanilla on hand.