I built this cocktail looking to find some sort of use for my creme de menthe that wasn't just a grasshopper.
As-is, I found it too rich and it turned my stomach - a rare experience for myself.
I highly recommend trying turning this into a long drink. Fill a glass with ice, pour this in, and fill with sparkling water - I used a grapefruit seltzer to great effect, but even unflavored would improve this drink greatly.
Otherwise, I would skip. I wanted *so* badly for this to be good as-is, but it is incredibly far from the mark. I would avoid experimenting with this unless you could turn it into a long drink if you don't like it.
I challenge you to make this with any fortified wine, similarly to how you can change the amaro used. It may come out sweeter, the walnut bitters others have mentioned would balance it out nicely.
Had a shot both with ice (as per the instructions) and neat, using Vecchio Amaro del Campo and Banhez mezcal, and it was amazing. Strangely enough, I think I may prefer it neat.