Cynar. Islay Scotch. Whole egg. As the name implies, the Black Diamond Flip is a cocktail that's for advanced drinkers only.
The disparate elements combine to create some interesting alchemy. The intense vegetal flavor of Cynar, the rich egg, and the smoky Scotch create a chocolate flavor that doesn't exist in any individual ingredient. The nutmeg, in addition to providing a nice aromatic quality, helps sustain the mid-palate as the initial chocolate flavor yields to the more expected bitter and peaty notes.
I've been citing this drink a lot lately with the release of Jacob Grier's book The Cocktail Collective, in which this cocktail is presented. The Black Diamond Flip has also appeared on the menu at Liberty in Seattle's Cap Hill neighborhood. Chris Bostick at The Varnish in Downtown LA also made an excellent rendition using Bowmore instead of Ardbeg.