1ouncebourbon(I used Old Forester Bourbon 86 Proof)
Combine sugar and espresso in a medium saucepan. Bring to a boil, stirring constantly, until the sugar is completely dissolved. Remove from heat. Transfer to a container and let cool completely. Set aside.
Place a large square ice cube or ice ball in a whiskey glass. Pour the espresso simple syrup and bitters then pour the bourbon. Garnish with an orange peel. Enjoy!