1. Bring water and sugar to boil in saucepan; boil, stirring occasionally, until sugar is dissolved. Cool to room temperature.
2. Puree the 3 cups raspberries in blender or food processor. Press through fine sieve into large bowl; discard seeds.
3. Add sugar syrup, raspberry puree, and champagne to bowl. Pour into 13x9-inch metal pan. Freeze, stirring every 30 minutes, until completely frozen, 3 to 5 hours.
4. To serve, spoon granite into chilled wine glasses. Serve with fresh raspberries and cookies, if desired. Makes 8 cups.