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...
For me 30ml of Campari is much too bitter. The perfect combinaison is 50ml of Bourbon 30ml sweet vermouth 15ml campari. And for those Who use Martini please stop. I recently changed my cheap martini for a martini reserva rubino and its definitely not the same drink. Don't hesitate and buy a good vermouth for your boulevardier negroni Manhattan and co