There isn’t a specific recipe, all you’ll need is some granulated sugar and vanilla beans. Place them together in a container and let them sit for a week or longer. The more vanilla beans you have in your sugar, the stronger the flavor.
For this batch, I dried out a few vanilla bean pods I had leftover from some homemade vanilla extract. Next time you use a vanilla bean in a recipe, set the pod aside to make some vanilla sugar. If you steeped the vanilla bean (in custard, for example), simply rinse it off and let it dry out on a paper towel for a few days before adding it to the sugar.