In a cocktail shaker, combine the lemon juice, maple syrup, bourbon, mezcal, apple cider, bitters, and egg white. Shake vigorously, without ice, for 1 minute. Then add a handful of ice and shake until cold.
Strain into a cocktail glass. The egg white foam will float to the top. Garnish with apple slices and a cinnamon stick, as desired.
Keyword apple, apple cider, bourbon, cocktail, fall, mezcal, sour