Step 1

For basil sugar syrup, stir sugar and 100ml water in a small saucepan over medium-high heat until sugar dissolves (3-5 minutes). Remove from heat and cool completely in fridge. Transfer to a blender, add basil with a pinch of salt and blend until basil is incorporated and mixture is green. Strain through a fine sieve into a container with a lid. Basil sugar syrup will keep in the fridge for up to 2 months.

Step 2

For cocktail, fill a cocktail shaker with ice, add gin, vermouth, lime juice and 30ml basil sugar syrup; shake until chilled. Fill a small glass with ice and strain cocktail into glass; top with sparkling wine. Serve garnished with basil leaves and a wedge of lime.