In a small jar with an airtight lid add gin and cardamom pods. Seal and store for 24 hours.
To make the rosemary simple syrup, bring sugar, water and 2 rosemary sprigs to a simmer in a small saucepan until sugar is dissolved. Remove from heat and allow to cool completely. Remove the rosemary and use right away, or store in an airtight container in the refrigerator for up to a week.
To make the cocktail pour rosemary syrup, infused gin and grapefruit juice over ice in a cocktail mixer and shake to combine.
Using a strainer, divide the mixture in two glasses filled with fresh ice.
Top with prosecco and garnish with a sprig of rosemary and a grapefruit peel. Cheers!
