Elderflower Bourbon Apple Cider

Nothing says autumn to me like the re-appearance of apple cider (sorry PSLs and pumpkin beers! ?) and the best way to drink it is obviously with bourbon. And, okay, maybe donuts. This is my absolute favorite cider cocktail -- it's the thing I most look forward to making when September rolls around, and stays my go-to all the way to Thanksgiving (probably because it's as easy to make as it to drink).