Shake all ingredients, except Stout, and strain into a martini glass. Finish with Stout. Garnish with espresso beans.
We use the Serpent Stout from Lost Abbey Brewing in San Diego, but you can always experiment with your favorite dark beer at home for unique twists. A nitrogenated beer like Guinness will give it a smooth, velvety texture while a traditional brew on carbon dioxide, like the Lost Abbey, will impart a crisp effervescence.