I changed the recipe a bit by using the mild Nonino amaro instead of vermouth, omitting the vanilla bitters and instead adding a dash of vanilla extract. The result was very pleasing, maybe a touch too sweet for my palate.
The perfect musical accompaniment to this is J J Cale's song of the same name. Late on a balmy evening sit back, next to your sweetheart, and enjoy the drink, the music and the warmth of her hand in yours. We had no Vanilla Bitters and so substituted Black Walnut...but just three drops.