Boil blackberries, and maple syrup, crushing berries gently as they cook until blackberries are broken down (this will take about 5 minutes).
Add lavender flowers (remove flowers from stem if they are fresh) and boil for 1 minute.
Remove from heat. Pour 1 tbsp. of blackberry sauce into a champagne flute, add a stem of fresh lavender and top with chilled Stella Rosa Prosecco.