Combine gin, lemon juice, simple syrup and egg white in a shaker.
Shake vigorously until the egg white emulsifies - approximately 20 seconds. (Skip this step if you omit the egg white.)
Add several ice cubes and shake until the liquids are mixed and chilled - approximately 20 seconds.
Strain into a coupe glass.
Use an eye dropper to place three drops on top of the cocktail. (Skip this step if you omit the Angostura bitters.)
Artfully swirl the three Angostura drops with a toothpick. (Skip this step if you omit the Angostura bitters.)
Notes
You can use another glass instead of a coupe glass.
You can omit the egg white if you're a vegan or if you're uncomfortable with ingesting raw eggs. You can alternatively replace the egg white with aquafaba.
You can also omit the aromatic bitters. We recommend garnishing this cocktail with a maraschino cherry or lemon twist if you omit the aromatic bitters.