In a small saucepan, combine the blackberries, sugar, and water. Bring to a boil on high heat, and then reduce to a simmer and let cook for approximately 15-17 minutes. The blackberries will become soft and bright in color and a pinkish purple syrup will form. Making sure it cooks down enough is essential to keeping the ombre effect.
1 cup fresh blackberries, 1 cup granulated sugar, 1 cup water
Take off of the heat and drain the blackberries, keeping the syrup in a separate bowl. Set both aside and allow to cool.
Once blackberries and simple syrup are cooled, spoon about 4 tablespoons of syrup into the bottom of each champagne flute.
Top with champagne.
750 mL champagne
Garnish with fresh blackberries or the cooked blackberries, and a sprig of rosemary.
4 sprigs fresh rosemary
Notes
Don't pour the champagne too fast, or you'll risk ruining the ombre effect.
Using frozen berries for the garnish step would add a refreshing twist and help keep the drinks cool if you're serving them outside.
The blackberry syrup can be made up to 1 week in advance and stored in an airtight container in the refrigerator until ready to use.