A long time ago there were no names for cocktails, and each drink consisted of booze, sugar, and water. If you went to a bar and wanted a drink with whiskey, you'd ask for a "whiskey cocktail." If you preferred a drink with gin, you'd order a "gin cocktail."
When absinthe was introduced to the scene, barmen started adding a couple of dashes to the whiskey cocktail; they called this variation the "improved whiskey cocktail." Fitzgerald takes the drink to 2011 by adding a few dashes of bitters and Luxardo Maraschino liqueur. It's potent, but it's perfectly balanced. Get his recipe after the break.