Excellent drink. I used Ancho Reyes, subbed agave syrup for the demerara and upped the lime to 20mL and it's wonderfully balanced.
Wow, this is *really* good. The rye and amaro (I used Averna because it's what I had on hand) split the spotlight, with the banana just a few steps back. But the Yellow Chartreuse is just enough to give it an herbal kick at the finish and really makes it shine. I followed Mike's advice and used a dash of angos, 2 drops of Bittermens xocolatl mole and 4 drops of ango orange bitters. One of my recent favorites.
Wonderful drink. Is the origin unknown? I enjoy reading the history/creator of the different cocktails.