Add Bourbon or Rye Whiskey, Simple Syrup, and bitters to a chilled rocks glass.
Stir until all ingredients are combined.
Add Ice to the cocktail and stir until chilled. (This will also allow the ice to melt slightly, which will release the amazing flavors in the drink)
Garnish with Maraschino Cherry and Orange Slice or Peel. (If using an orange peel, twist it above the cocktail to release the zest and then rub it lightly around the rim of the glass before placing it in the drink)