Prepare Meringue and Raspberry Puree. In chilled bowl beat cream, sugar, and vanilla until soft peaks form; spread onto meringue. Top with berries and chocolate. Drizzle raspberry puree onto plates. Serve meringue wedges atop puree. Serves 10.
Allow egg whites to stand at room temperature for 30 minutes. Preheat oven to 350 degrees F. Cover a very large baking sheet with parchment paper or foil. Draw a 10-inch diameter circle on paper, leaving a 1- to 2-inch margin outside the circle; set aside. In large mixing bowl beat egg whites with electric mixer on medium to high speed until soft peaks form (tips curl). Add sugar, 1 tablespoon at a time, beating on high speed until stiff peaks form (tips stand straight) and sugar is dissolved. Gently fold in bittersweet chocolate, unsweetened cocoa powder, and balsamic vinegar. Spread meringue on circle on prepared baking sheet. Place in oven. Immediately reduce oven temperature to 300 degrees F. Bake for 1 hour. Remove from oven; cool completely on baking sheet on rack. Carefully remove meringue from parchment; transfer to a serving platter.
In a blender place fresh raspberries. Cover and blend until pureed; sieve, if desired. Transfer to a small bowl. Stir in sugar.