Mother'S Oh And Ah Cake
["3 egg yolks", "1 c. thick sour cream", "1 1/2 c. granulated sugar", "2 (1 oz.) sq. unsweetened chocolate", "1/4 c. hot water", "1 tsp. vanilla", "1 3/4 c. cake flour", "1/4 tsp. salt", "1 tsp. soda", "3 stiffly beaten egg whites"]
["Beat egg yolks and cream.", "Add sugar gradually and beat until thick.", "Dissolve chocolate in hot water; cool.", "Add to first mixture.", "Add flour, sifted 3 times with salt and soda.", "Fold in egg whites.", "Bake in two greased 8-inch layer pans in a moderate oven at 350\u00b0 for 30 minutes."]
["egg yolks", "sour cream", "sugar", "unsweetened chocolate", "hot water", "vanilla", "cake flour", "salt", "soda", "egg whites"]