Shake dry first (if using egg white). Add everything except ice to a cocktail shaker and shake hard for about 15 seconds. This builds a silky foam.
Shake again with ice. Add ice and shake for another 15 seconds until well chilled.
Strain and serve. Strain into a rocks glass over a large ice cube, or into a chilled coupe for a more elegant look. Add a dash of bitters on top of the foam, then garnish with an apple slice and a cinnamon stick.
Optional: No egg white? Skip the dry shake and shake once with ice. You will still get a bright, balanced drink, just a little less velvety. with lemon wheel and/or cherry