Combine the gin, pumpkin spice syrup, lemon juice, and egg whites in a cocktail shaker without ice. Secure the lid and shake vigorously for 15 seconds to build a frothy texture from the egg whites.

Add a handful of ice cubes to the shaker. Shake again for another 10 to 15 seconds until the mixture is well chilled.

Strain the drink into four chilled glasses using a fine mesh strainer to catch any ice shards and preserve the foam on top.

Lightly dust each glass with ground nutmeg before serving.