Preheat oven to 350 degrees. Spray 13x9 inch baking pan with cooking spray. In large saucepan, over low heat, combine milk, cocoa and chocolate morsels. Stir until morsels are melted; remove from heat. Stir in egg whites, flour, baking powder and vanilla, mixing well. Turn into prepared pan. Bake 20 minutes, or until center is set. Cool completely on wire rack. To serve, cut into squares. Sprinkle with confectioner's sugar, if desired. Nutritional Information: Calories: 120; Protein 3g; Carbohydrates 20g; Fat 3g; Sodium 60mg. ----