German Chocolate Cake
["1/2 c. boiling water", "1 (4 oz.) bar sweet cooking chocolate", "2 c. sugar", "1 c. margarine, softened", "4 egg yolks", "1 tsp. vanilla", "2 1/4 c. all-purpose flour *", "1 tsp. baking soda", "1 tsp. salt", "1 c. buttermilk", "4 egg whites, stiffly beaten"]
["*Do not use self-rising flour with this recipe."]
["boiling water", "bar sweet cooking chocolate", "sugar", "margarine", "egg yolks", "vanilla", "all-purpose flour", "baking soda", "salt", "buttermilk", "egg whites"]