Muddle together 1/3 cup fresh blueberries, Blueberry liqueur and simple syrup. Add the Bourbon, stir well and top with lots of crushed ice. Garnish with fresh mint.
(Optional Mint Simple Syrup: Bring equal parts sugar, water and a handful of mint leaves to a boil, stir frequently. Turn off heat, set aside to cool and strain / remove the fresh mint.)