Sponge Cake with Blueberry Topping

Ingredients (17)

• 6 large eggs, separated
• 1-1/2 cups sugar
• 3/4 cup orange juice
• 1-1/2 cups all-purpose flour
• 1-1/2 teaspoons baking powder
• 1/4 teaspoon cream of tartar
• BLUEBERRY TOPPING:
• 1/2 cup sugar
• 2 teaspoons cornstarch
• 1 tablespoon grated orange zest
• 1/2 cup orange juice
• 2 cups fresh or frozen blueberries
• SOUR CREAM TOPPING:
• 2 cups sour cream
• 1 tablespoon confectioners' sugar
• 1 teaspoon vanilla extract
• grated orange zest, optional