The smoothest, oaky-with-hints-of-vanilla-and-butterscotch Manhattan you can possibly imagine. There are great sources to buy your own barrels online, this recipe uses a 2 litre barrel.
If using a new barrel, prepare it according to the manufacturer's direction. Generally you need to soak it in water for a few hours to ensure a good seal. Drain the water and the barrel is ready for action!
Ensure barrel spout is closed. Place funnel into top hole of barrel. Add the Bourbon, Vermouth and bitters. Place the cork into the top of the barrel to seal. Allow 6–8 weeks for aging, giving the barrel a 1/4 turn each week.
Test a Manhattan: remove the cork from the top to allow the liquid to flow; get a cocktail shaker ready and fill straight from the barrel. Add ice, shake, and pour into cocktail glass. Test sample for depth of flavour and aroma. If desired, continue to age to bring out more oak flavour. If you are happy with the taste, pour into bottles. The barrel can now be used to make another batch—perhaps next time you'd like to adjust the bitters to suit your taste, or switch up the brands of Bourbon or Vermouth.
Bourbon soaked cherries add the perfect finishing touch when you serve up a glass. Enjoy!