4    Eggs -- separated; whites

           -beaten stiff
    1/2 c  Sugar

      4 oz Baking chocolate -- melted

    1/2 c  Flour

      1 tb Potato flour (*)

  Beat together yolks and flour 'til yellow and creamy.  Fold in whites. Fold
  in chocolate. Sift flours together and fold them in with other mixture.
  Butter and sugar an 8" sq. pan.  Pour in batter, bake at 375 degrees for 35
  minutes (or until you can poke it with a skewer and pull it out dry.)