Place the egg white, gin, lemon juice, and Simple Syrup in a shaker filled with ice. Shake vigorously until frothy and cold, and strain into a tall, skinny glass. Top with Champagne and serve.
Simple Syrup:
In a small saucepan, simmer 1 cup of sugar and 1 cup of water over low heat until sugar is dissolved. Allow to cool, and store in the refrigerator.