Prepare the decoration. Remove the leaves from the bottom half of the rosemary springs. Save the leaves for the syrup. Place two blackberries on each rosemary spring. and freeze.
Place blackberries, sugar, water, and rosemary leaves in a saucepan. Cook for 15-20 minutes or until you get a syrupy consistency.
Drain through a sieve to remove the pits and cool the syrup.
Pour chilled champagne into champagne glasses, then tilt each glass 45 degrees and pour 2 TBSP syrup on the sides of the glass, so it slides to the bottom. Decorate with blackberries on rosemary springs.