2 oz. Gin
1 oz. simple syrup (or 2 tsp. superfine sugar)
1 oz. lemon juice
Brut Champagne or other dry sparkling wine
Combine gin, sugar, and lemon juice in a cocktail shaker filled with ice.
Shake vigorously and strain into an iced highball.
Fill with Champagne.
Garnish with a twist of lemon.
The combination was said to have such a kick that it felt like being shelled with the powerful French 75mm field gun, also called a “75 Cocktail”, or “Soixante Quinze” in French