From Death & Co
Shake all the ingredients (except the champagne and grapefruit coin) with ice, then double strain into a coupe.
Squeeze the grapefruit coin over the drink and discard.
Top with champagne.
No garnish.
Created by Alex Day, 2008. A play on the French 75 (page 143), making it more about the gin and less about citrus. Grapefruit and maple syrup work so well together.