Sort blueberries, discarding any stems and decayed fruit; rinse and drain fresh berries. In a 1 1/2- to 2-quart pan, combine 1/2 cup of the blueberries, sugar, cornstarch, orange and lemon peel, orange juice, and lemon juice. Stir over high heat until boiling, about 3 minutes. Add remaining berries and stir just until mixture boils again. Stir in vanilla. Pour into bowls. Serve hot, warm, or cool, topped with French Cream.