For frosting, in a medium saucepan combine whipping cream and chocolate. Cook, stirring occasionally, over low heat until chocolate is completely melted and smooth. Transfer to a large mixing bowl; cover and refrigerate until completely chilled, at least 2 hours.

Meanwhile, grease and flour two 9x1-1/2-inch or 8x1-1/2-inch round cake pans; set aside. Prepare cake mix according to package directions using egg whites. Spoon about 1-1/2 cups of batter into each cake pan. Sift cocoa over batter remaining in bowl; stir until blended. Spoon on cake mix in pans; swirl gently to marble and to spread batter evenly. Bake according to package directions except check cakes several minutes before minimum time indicated on package.* Let cakes cool on wire rack for 10 minutes. Remove cakes from pans; cool completely on wire racks.

Add cream cheese to chilled white chocolate mixture; beat with an electric mixer until smooth. Gradually add powdered sugar, beating until sugar is completely combined. (Mixture should hold soft peaks; do not overbeat.) Use immediately.

Place one cake layer on a serving platter. Frost with about 3/4 cup frosting. Top with second cake layer. Frost top and sides of cake.

Serve immediately or cover and chill until serving time (up to 4 hours). To serve, garnish cake with Sugared Rosemary and Cranberries and crushed biscotti, if desired. Makes 12 servings.

Lightly spray several rosemary sprigs and cranberries with nonstick cooking spray. Sprinkle granulated sugar on rosemary; roll cranberries in a small amount of granulated sugar to coat. Place on waxed paper for at least 1 hour before using. This is a decorative, not edible, garnish.

The added cocoa makes the cakes bake in a shorter time.