Place the vanilla beans straight into the bottle of vodka and replace the cap. Slicing each bean lengthwise first is fine but isn't necessary and doesn't seem to make much of a difference to the flavor.

Note that each bean should be fully submerged in the vodka.

Leave the vodka to slowly extract the vanilla flavor from the beans for at least 6 weeks in a dimly lit place like a cabinet that isn't too warm. Ideally, 8 weeks is required for the majority of the vanilla flavor to be extracted from the beans. Gently shaking the bottle occasionally will help move the process along.

After 6-8 weeks, carefully remove the vanilla beans and pour the vanilla extract into 8 oz amber bottles if you will be giving to family or friends. If making the vanilla extract for yourself, simply place the vodka bottle into the pantry (appropriately labeled) for your personal use.