Preparation Puree 6 cups blackberries in processor. Pour puree into fine strainer set over 4-cup measuring cup. Press on solids to extract as much juice as possible. Discard solids in strainer. Measure 3 cups puree (reserve any remaining puree for another use). Stir 1 cup grape juice, 1 cup sugar and lemon peel into blackberry puree. Pour remaining 7 tablespoons grape juice into small saucepan. Sprinkle gelatin over; let stand until gelatin softens, about 10 minutes. Stir gelatin mixture over medium-low heat until gelatin dissolves, about 1 minute (do not boil). Gradually whisk warm gelatin mixture into puree mixture. Transfer to 8 x 8 x 2-inch glass baking dish. Cover and refrigerate overnight. (Can be made 2 days ahead. Keep chilled.) Mix remaining 3 cups blackberries and 4 tablespoons sugar in medium bowl. Let stand at room temperature at least 1 hour and up to 3 hours, tossing occasionally. Spoon generous 1/4 cup blackberry gelatin into each of 8 parfait glasses or wine glasses. Top with a few sweetened blackberries. Spoon about 1/3 cup Vanilla Whipped Cream over. Repeat layering. Top with a few more berries. Garnish with mint and serve.
Preparation Puree 6 cups blackberries in processor. Pour puree into fine strainer set over 4-cup measuring cup. Press on solids to extract as much juice as possible. Discard solids in strainer. Measure 3 cups puree (reserve any remaining puree for another use). Stir 1 cup grape juice, 1 cup sugar and lemon peel into blackberry puree. Pour remaining 7 tablespoons grape juice into small saucepan. Sprinkle gelatin over; let stand until gelatin softens, about 10 minutes. Stir gelatin mixture over medium-low heat until gelatin dissolves, about 1 minute (do not boil). Gradually whisk warm gelatin mixture into puree mixture. Transfer to 8 x 8 x 2-inch glass baking dish. Cover and refrigerate overnight. (Can be made 2 days ahead. Keep chilled.) Mix remaining 3 cups blackberries and 4 tablespoons sugar in medium bowl. Let stand at room temperature at least 1 hour and up to 3 hours, tossing occasionally. Spoon generous 1/4 cup blackberry gelatin into each of 8 parfait glasses or wine glasses. Top with a few sweetened blackberries. Spoon about 1/3 cup Vanilla Whipped Cream over. Repeat layering. Top with a few more berries. Garnish with mint and serve.