Ramos Gin Fizz is one of those well-regarded classic cocktails that you will never see on any cocktail menus (except maybe in its hometown of New Orleans). Reason being, it's a damn tasty drink but it is also a horrific pain in the ass. Egg is finicky enough to integrate that it takes its own technique to properly emulsify; add cream, and you've got a drink that takes at least a minute of sustained shaking to get right. That's troublesome even at home (after every round, I swear my arms are going to fall off) but I can't even imagine cranking out dozens each night.
Still, every now and again a floral, refreshing, richly textured cocktail is worth it. Winter must be eroding my brain again.
2 oz gin (I'd have used Old Tom if I had any)
1 oz lemon juice
3/4 oz blueberry syrup
3/4 oz half-and-half
3 drops rose water
1 small egg white (or 1/2 a large egg white)
Dry shake (as in, combine everything and shake without ice) until you can't take it anymore, then add ice and shake some more. Keep shaking. Do your arms hurt yet? Keep shaking. You're not done. Keep shaking. Curse eggs and dairy, curse yourself for choosing such a beverage, curse your cruel and capricious God. Keep shaking.
After a subjective eternity, strain into a tall, footed fizz glass if you've got one (or your thinnest, tallest glass if you don't) and top off with 2-3 oz of chilled soda water. Stir gently, garnish with a little drizzle of extra blueberry syrup for super-fanciness. Such a difficult cocktail should not go undecorated.