In a small saucepan, combine the sugar, cranberries, juice, rosemary and ginger. Bring to a boil and simmer (about 30 minutes) until the cranberries soften and burst. Remove the rosemary sprigs and finely mash the cranberries. Simmer a little more until the mixture becomes thick and viscous (approx. 15 – 20 minutes). Remove from heat and let the syrup cool completely.
Add 2-3 tablespoons of the cranberry mixture to each glass. Pour over the chilled sparkling wine at the last minute. Cheers!