To a cocktail shaker, add the bourbon, simple syrup, egg, and ice. Close and seal the shaker.
Shake vigorously A LOT! You should feel tired by the time your done (at least 1-2 minutes).
Strain the cocktail into a coupe or champagne saucer glass.
Top with freshly grated nutmeg. Serve immediately.
To make simple syrup, combine equal parts water and sugar in a saucepan. Bring to a simmer and cook until sugar is dissolved. Remove from heat and cool to room temperature before using.If you can't get your hands on whole nutmeg, ground nutmeg will work okay too.