How to Make It
Preheat oven to 350°. Lightly grease 3 (9-inch) round cake pans; line bottoms with parchment paper, and lightly grease paper.
Microwave chocolate baking bars and 1/2 cup water in a large microwave-safe bowl at HIGH for 1 to 1 1/2 minutes or until chocolate is melted and smooth, stirring once halfway through.
Combine flour and next 2 ingredients in a medium bowl.
Beat egg whites at high speed until stiff peaks form; gently fold into batter. Pour batter into prepared pans. Bake at 350° for 25 to 30 minutes or until a wooden pick inserted in center comes out clean.
Remove from oven, and run a knife around outer edge of cake layers to loosen from sides of pans. Cool in pans on wire racks 15 minutes. Remove from pans to wire racks; discard parchment paper. Cool completely (about 1 hour).
Spread Coconut-Pecan Frosting between layers and on top and sides of cake. Garnish, if desired, with chocolate-dipped toasted pecan halves.