Double Chocolate Brownies

Preheat oven to 350°F. Coat a 9-by-13-inch baking pan with cooking spray. Melt chocolate and butter in a double boiler over barely simmering water. (Alternatively, place in a small microwave-safe bowl and microwave on Medium, stirring every 30 seconds, until melted and smooth.) Whisk flour, cocoa and salt in a medium bowl. Beat egg whites, eggs and brown sugar in a large mixing bowl with an electric mixer. Add applesauce, oil and vanilla; beat until blended. (See Variation.) Add the chocolate-butter mixture; beat until blended. Add the flour mixture and mix just until moistened. Stir in chocolate chips. Scrape the batter into the prepared pan, spreading evenly. Sprinkle with nuts, if desired. Bake the brownies until the top springs back when touched lightly, 20 to 25 minutes. Transfer to a wire rack and let cool completely. Cut into bars. Variation: For a mocha flavor, in Step 4 stir in 4 teaspoons instant coffee granules dissolved in 2 tablespoons hot water.