A nice, nuanced cocktail that has traveled far from a Manhattan - but not exceptional.
A melange of flavors - the amaro (I used Averna) leads with a slightly sweet cola and licorice (among other spices & herbs) with mild bitterness following immediately. The spicy rye emerges in the mid, complemented by a *hint* of the dried fruit/raisin of the port, and the finish is dominated by the rye, with the Averna long gone. Smooth and full-bodied, but not syrupy, with some boozy heat emerging early and lasting into the finish.
I see others used black walnut bitters (an excellent suggestion!), and serving over ice to allow for some extended sipping and modest dilution - another great suggestion.