Cream sugar and butter, then add egg yolks and stir well. Add milk. Melt the sweet chocolate and add to the mixture. Sift cake flour once, then measure (do not skip this step!). Add baking powder to flour and sift together 3 or 4 times. Add to cake mixture. Stir in nut meats, vanilla, and salt. Beat egg whites until they stand in peaks, then fold into the chocolate mixture. Pour mixture into 9- x 13-inch pan or two (8- or 9-inch) round layer pans. Bake at 350 degrees for 45 minutes, or until toothpick comes out clean. For frosting, beat ingredients together until fluffy. Frost cake with Chocolate Deluxe Icing.
Note: This is a very temperamental cake and cannot be beaten too hard. If using an electric mixer, use either slow or medium speed.