1 1/2 oz gin
1/2 oz St. Germain elderflower liqueur
1/4 oz simple syrup
3/4 oz lemon juice
1 egg white
2 dashes grapefruit bitters
Froth the egg white in a mixing glass by shaking (no ice) or with a hand held frother. Add ice and the rest of the ingredients, shake hard and double strain into a cocktail glass.
This drink is just a variation of the Vieux Mot (old word) from PDT, I only added the bitters and the egg. The original drink is so good it really doesn't need any tinkering with though.