Slowly sift the powdered sugar into the melting butter. Simmer until fully combined, and then add the bourbon and vanilla. Continue to simmer for a moment more to cook off the alcohol taste.
Pour over buns hot, or let cool to room temperature and use as a spreadable frosting.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.
Recipe courtesy of Jane's Sweet Buns, 2011