Drinking this now. While enjoyable, I find that the elderflower is very faint and honestly if I didn't make this drink I would of had not really noticed. I think I would prefer this with 2oz rye, 3/4oz punt e mes, 1/2 oz elderflower instead.... This just in: yes I enjoy it this way more, the punt e mes doesn't overpower the rye and the elderflower now has that "what's that flavor" role.

upped the rye as suggested

Salt can also cut bitterness. Would a tiny pinch of salt bring out the floweriness of the citrus?

Salt might work, although I tend to think of using it more with savory flavors like Cynar. I would like to re-try this with Pierre Ferrand Dry Curacao in lieu of triple sec. I think the brandy base and the modest sugar would both help.

I've seen salt in recipes with Cynar before, and it's easy to imagine it working in lots of places where one wants to emphasize the savoriness of a cocktail. (Salt as cocktail umami?) Now, I've seen salt and citrus paired successfully (read: to the citrus's advantage) in cookery before, but never in mixology--not that my experience in either domain is expert-level. On the other hand, I've pinched salt straight into Cointreau, which, if done in a sufficiently restrained way, makes it interestingly more citrusy: the sweetness and bitterness recede, and the "flavor" presses forward--especially the flowery, nasal quality of the citrus.

I'm not familiar with Pierre Ferrand Dry Curaçao. I can see why a bit of sugar might balance things the way you want. But why the brandy base?

I wasn't crazy about this as written; adding .75 oz lemon juice made it much better.

This one of those classic cocktails that requires some refinement for modern tastes. PDT version of 2oz, 1/4 oz, 1/4 oz is a fine ratio. While a decent 3 stars I like Christina's addition of lemon juice. I used about a tsp of lemon juice and used a 1/2 oz Benedictine based off the PDT version. It helped bridge the herbacous apple profile.

It is a much better drink with Calvados, in my opinion. We always use Calvados -- with the same 2:1:1 ratios as the original recipe.

The PDT modernization mentioned above is on this site. Or Punch has a similar update of the recipe by Deke Dunne that splits the base with cognac. More specifically: 

• 1 oz apple brandy
• 3/4 oz VSOP cognac
• scant 1/4 oz of each of the liqueurs
• 2 dashes Ango

This is tasty.  I think Derek Brown's original is a bit better than this particular recipe.

Revised to match original recipe. Previously published here as 1 oz each bourbon, sherry, port (regular, presumably), and Ango. Garnish with cherry and squeezed lemon. My guess is that the need for the simple varies with the sherry and port used.

Halved the simple to 1/4oz per a more recent tweet from Derek Brown.

Cleaned up a little - moved Bols from the notes to the brand, removed fresh from the notes on the lemon juice. Added history section - this is a bizarre drink.

We tried this and enjoyed it. Because my fiance has acid reflux problems with lemon juice, I halved the amount, and based on our opinions compared to the original poster's comments, it seems to have created a more balanced cocktail,

Is this your own creation Dan?

No, I believe that I imported this from another user's database. I cannot find a good on-line reference for the quantities, although the ingredients seem correct. I don't find the syrup mentioned. I updated the attribution. If anyone can confirm the ingredients and quantities, I'd love to update the recipe and mark it as authentic.

Made stirred with Makers Mark and worked well. Added a dash of cherry vanilla bitters which rounded it out nicely 

Would dial the lime back to 1/2 oz.