Pour in gin, lemon juice and simple syrup and shake for about 20 seconds.
Strain into a chilled Champagne flute and fill with Champagne.
Add a lemon peel twist for garnish.
Notes
Even though you are mixing, use a quality Champagne. The taste of inferior spirits will come through.I prefer a dry or brut champagne, as it will pair better with the botanical gin.You can substitute Cognac for the gin (but then you are getting close to a Champagne Cocktail)