Using a small sauce pan, heat the water, sugar and blackberries until it begins to boil. Stirring constantly. Continue to simmer on low for 10 more minutes.
Remove the blackberry syrup from the burner and allow to cool completely.
Spoon 2 Tbsp. of the blackberry syrup into the bottoms of each glass.
Pour chilled Prosecco over the syrup in the glass and garnish with two blackberries and a sprig of fresh mint. Feel free to add ice or use loose mint leaves instead of a sprig if you prefer.
Sip and Enjoy. Cheers!