4 egg yolks
1/2 c. sugar
4 egg whites, beaten stiff
4 sqs. cooking chocolate
1/2 c. flour
1 tbsp. potato flour
1 tbsp. sugar

Beat together egg yolks and sugar until yellow in color and creamy. Fold in beaten egg whites. Melt chocolate over low flame and add to egg mixture. Sift the two flours together and add gently to the batter. Butter an 8 inch square, 3 inches high, cake pan; sprinkle buttered surface of pan with 1 tablespoon sugar, spread around as evenly as possible and shake out surplus sugar. Pour in batter and bake in moderate oven (375 degrees) for 35 minutes.