If the Old Fashioned was the spark of life that would eventually become the modern cocktail, then the Improved Cocktail was the amoeba. Jerry Thomas himself first documented it as more exotic ingredients become more readily available for use in mixing drinks in the late 19th Century.
The Old Fashioned cocktail, as we've said, is a way to season your spirit and to make it a bit more palatable. The Improved Cocktail builds upon that recipe to enhance the complexity just a bit. This time around, all you need to add to your Old Fashioned to make it Improved is a bit of Absinthe and Maraschino liqueur.
2 oz spirit
1 dash simple syrup
1 dash aromatic bitters
1 dash Maraschino
1 dash absinthe
Stir with ice and strain into a cocktail glass. Garnish with lemon twist.
It doesn't sound like much, but Thomas knew what he was doing when he codified this thing into the printing press. I'll reiterate that I'm not fanboy of Maraschino or absinthe either, for that matter, and yet the Improved Cocktail impresses me every time I make it.
Much like the Old Fashioned, you can swap the spirit for whatever you like (and the bitters and garnish, accordingly) and it will usually work. My favorite Improved Cocktail is made with my beloved Cruzan Black Strap rum. There's something about the pungency of the rum's molasses flavors that stand up to the strong absinthe and Maraschino like no other spirit I've had so far(except for maybe Scotch whisky). I also tend to like my Improved Cocktails on the rocks.
I wrote about humility a while back, and why I wasn't giving my own name to a cocktail that I thought didn't deserve one. Since then, I've gotten encouragement to shed humility by going ahead and naming cocktails that I've made, even if doing so seemed a bit exorbitant.
So technically you could call this an Improved Black Strap Cocktail on the rocks, but instead it will be...
1.5-2 oz Cruzan Black Strap rum
heavy dash simple syrup
heavy dash aromatic bitters
heavy dash Maraschino
heavy dash absinthe
Build over ice in small tumbler. Garnish with orange twist.