For me, the orange blossom water is overpowering to the point of ruining the drink. Will have to try it again with less. The ingredients are all very sweet, with little else to add complexity. I fail to see any good reason to use sugar (which will never fully dissolve) rather than a sugar syrup - frankly, I would probably omit the sugar altogether.
I saw this recipe on PUNCH calling for just an egg white before finding this entry here... A whole egg sounds interesting. Might have to alter the presentation though... I made this as instructed (sans float) but over 3-4 cubes of ice in the glass. The measure of Chartreuse alarmed me, but the end result came across as one of the best showcases of this main ingredient.
I made this with the whole egg and liked it a lot. Felt as the yolk swallowed the intensity of the Chartreuse. The orange water really makes the difference. Do not want to change the recipe.
It's what's known as a "Reverse Dry Shake". Shake all ingredients (including egg). Then strain from large shaker tin into now empty small shaker tin. Discard ice left in the large shaker tin, reseal shaker without adding ice, and shake again. Fine strain into your glass.