Tastes differ, but the fact that folks have found the need to add 1/4 oz of Grand Marnier or Dry Curacao to the original recipe is itself a commentary on the dry high ABV nature of the drink, particularly if using 100 proof rye. One of the things I have noticed is that with recipes that are past about 80 proof prior to ice dilution, the alcohol heat often dominates, suppressing other flavors. It can be the difference between a "meh" cocktail like this one, or something I want to have again. FWIW, I generally make Black Manhattan's with 90 proof rye...which is the same as using an ounce each of 100 rye and 80 cognac here. The difference in heat with this recipe is that half the 58 proof Averna is replaced by 80 proof Marnier/Curacao and 78 proof Fernet.

This is not "too hot" for me, personally. Perhaps some of that is a personal preference for strong brown drink (eyes the 108 proof rye I used for this).

But: there's also as much sweetness in the ounce of modifiers as there is in a typical black Manhattan and most cognacs will both knock down the proof and knock up the sweetness.

I liked it

I’m referring to the recipe I first discovered here: https://kindredcocktails.com/cocktail/boulevardon

This one is high ABV, nearly 83 proof before ice dilution if using a 100 proof rye. While it isn't bad, in this case it doesn't quite work because the drink is also semi-dry. (Then again, Don Draper had become an embarrassing lush midway through....so the potency is thematic.) Shockingly, Fernet is mostly hidden behind the masking alcohol heat. The dry Curacao seems to lend an odd bitter orange chemical aspect in the finish. Averna's character is somewhat muted. I am not sure what the solution is, perhaps using an 86 proof rye, and a low ABV orange aperitivo (vs. 80 proof dry Curacao), would improve the character while retaining key elements.

Curated: Dead reference link updated with archive link to the original. Corrected long standing error in bitters quantity vs. the reference, should be 3 drops, not 3 dashes. From what I can tell from making it, 3 dashes makes it too orange in color to match the hue of Chilcano de Pescado soup. Some recipes use no bitters, but most recipes call for 2 to 4 drops of bitters and I suspect some of the recipes calling for 2 dashes might have been influenced by the drop vs. dash error here. A Spanish language bartender video I watched from ~2010 states 3 dashes, but does three very small dashes--similar to what one might get from a Japanese dasher bottle. Interestingly, Simon Difford's 2019 recipe and a 2020 Forbes article listed 3 dashes of Amargo Chuncho bitters--which is the bitters I suggest for this, although not in such a large quantity.