Fill a cocktail shaker with ice.
Combine the gin, simple syrup and lemon juice in the cocktail shaker and shake vigorously for one minute.
Pour the mixture from the cocktail shaker into a coupe glass or champagne flute.
Fill the rest of the glass with your sparkling wine/prosecco. This is usually about 3 ounces of liquid.
Optional: Garnish with a lemon peel.