Chill a cocktail glass or coupe in the freezer at least ten minutes. Separate one egg, discarding the yolk. Lightly mix the egg white with a fork – this’ll help you measure it out.
In an empty shaker, add all ingredients. Make sure you have a good, tight seal (egg whites can foam up and expand when shaken). Shake without ice for 20 seconds to blend. Add a few ice cubes and shake again, hard, for at least 30 seconds. Double-strain into the chilled glass using a fine-mesh strainer.
Allow the egg foam to rise to the top (you can also spoon some residual foam out from the shaker) and, in a ring, drop:
8 drops Angostura bitters
Swirl the Angostura bitters with a cocktail pick to decorate the top of the drink. Garnish with a lemon wheel and Maraschino cherry pinned together with a cocktail pick.