Fill a shaker with ice. Pour in the gin, lemon juice, and simple syrup.
Stir well, but do not shake.
Pour the cocktail into a champagne flute. Fill the top of the glass with champagne, approximately 1 to 2 ounces. Add a lemon twist to the glass and serve.
Video
Notes
This recipe makes one average. Double, triple, or quadruple based on the size of your shaker.