Combine watermelon puree, sugar, mint leaves and salt in a sauce pan over medium heat. Simmer for 10-15 minutes or until the sugar has dissolved completely.

Strain out watermelon solids through a fine sieve lined with a cheese cloth to ensure that all solids are removed.

Set aside to cool before adding to your cocktail. Store in the fridge in an airtight container for up to 1 month.

Add the vodka, simple syrup, bitters, vanilla and mint leaf to a shaker with ice. Shake for 30 seconds or until the outside of the shaker feels cold.

Strain half the contents into a glass with a large ice cube (or straight up if desired). Add 1 oz of Prosecco, then add the remaining contents and top off with Prosecco. Garnish with a mint leaf and enjoy!