occasionally, until sugar dissolves. Increase heat and boil syrup 2 minutes. Cool completely. Mix 2.5 cups syrup with cream. Refrigerate until well chilled. Process blackberry mixture in ice cream maker according to manufacturer's instructions; ice cream will be soft. Freeze in covered container several hours to mellow flavors. Garnish with fresh berries and mint leaves. *Can substitute unsweetened frozen blackberries, thawed.