Old-Fashioned Diner Cake Dec 31, 1999 INGREDIENTS:Cake: 4 oz. margarine ½ cup vegetable shortening 2 cups sugar 3/8 cup egg yolks 1/3 cup egg whites 1 tsp. baking soda ½ tsp. salt 2 cups flour 1 cup buttermilk ¾ tsp. vanillaFrosting: 4 ½ oz. butter ¾ cup...