French 75 is a cocktail made from gin, champagne, lemon juice, and sugar. It is also called a 75 Cocktail, or in French simply a Soixante Quinze. The drink dates to World War I, and an early form was created in 1915 at the New York Bar in Paris—later Harry's New York Bar—by barman Harry MacElhone. The combination was said to have such a kick that it felt like being shelled with the powerful French 75mm field gun.
Add the gin, lemon juice and simple syrup to a shaker with ice and shake until well-chilled.
Strain into a Champagne flute.
Top with the Champagne.
Garnish with a lemon twist.