The black jack is a fresh take on a classic coffee cocktail, first credited to sommelier jacques straub of kentuckys pendennis club way back in 1914. The original equal-parts recipe didnt jibe well with the modern palate, so the folks at legendary speakeasy pdt reworked the recipe for a better balance. In the pdt cocktail book, coffee concentrate is called for in place of the cold coffee required in the original black jack recipe. This is a good choice, and we recommend it if you have it. Its a bit less watery than regular drip or french press coffee, but either of those will do in a pinch. If you like a sweeter coffee, feel free to double the amount of syrup used, or serve the drink in a sugar-rimmed glass.