Divide ice cubes between 4 tumblers. Garnish each glass with 1 orange slice and 2 maraschino cherries.
In a pitcher, blend the bourbon, vermouth and bitters and pour into tumblers.
Note: If you like your cocktails to be a bit sweeter, you can stir 3 teaspoons of sugar into the pitcher before pouring the drinks.
Recipe courtesy of Michael Chiarello