Preheat the oven to 350F. Grease and lightly flour 2-8” round cake pans. Make the box of cake mix according to the box directions. Stir in the chocolate chips. Pour the batter into the prepared cake pans and bake 20-25 minutes, or until a tester put in the middle of the cake comes out clean. Cool in the pans for 10 minutes. Turn out onto racks and cool completely. Beat the 6 egg whites until very stiff, adding the sugar while beating. Fold the melted, cooled chocolate into the stiff egg whites and sugar. Fill and cover the cake with the chocolate mousse topping. Sprinkle the top and the sides with grated chocolate. Serves 10.