Basically, a Negroni with bourbon replacing gin. The original 1927 recipe calls for equal parts, but I've previously favoured a 3:2:2 (45ml bourbon, 30ml...
My favorite riff on Negroni. Choosing the bourbon wisely provides lots of flexibility, its flavor will define the drink. While I love spicy ones I'd choose a bit more gentle for this one, paired with Carpano Antica Formula. Or go with spicy or even rye + martini and rossi.