Cut a thin piece of rind off the lemon and set aside for garnish, then juice the lemon.
Add your sugar and water to a pan, simmering until the two are mixed and form a simple syrup.
Separate your egg yolk from the white. Add the white to the cocktail shaker, saving the yolk for a hungover omelette the next day.
Dry shake your white in a shaker to achieve a foamy texture, then add a measure of the lemon juice, a measure of the simple syrup, a double shot of whiskey (or single depending how strong you want it) and some ice.
Shake the cocktail shaker for 30 seconds, then pour it out into your glass.
Garnish with a lemon and enjoy.