Crème de cassis (krehm deuh kah-SEES) is a liqueur made with black currant syrup.
Combine first 3 ingredients in a large pitcher. Chill until ready to serve.
Before serving, add sparkling water and Champagne to currant mixture; stir well. Divide blackberries evenly among 9 glasses. Top each serving with about 1 cup Champagne mixture. Serve immediately.