PREHEAT oven to 350°F. Line bottoms of 3 (9-inch) round cake pans with wax paper. Mix chocolate and boiling water; stir until chocolate is completely melted. Cool.

MIX flour, baking soda and salt; set aside. Beat butter and sugar in large bowl with electric mixer on medium speed until light and fluffy. Add egg yolks, 1 at a time, beating well after each addition. Stir in chocolate and vanilla. Add flour mixture alternately with buttermilk, beating well after each addition.

BEAT egg whites in small bowl with electric mixer on high speed until stiff peaks form. Gently stir into batter. Pour evenly into prepared pans.

BAKE 35 minutes or until toothpick inserted in centers comes out clean. Immediately run spatula around side between cakes and side of pans. Cool 15 minutes; remove from pans. Remove wax paper. Cool completely on wire racks. Spread Coconut-Pecan Filling and Frosting between layers and over top of cake. (NOTE: Nutrition information is for cake only.)