1 c  Sifted all-purpose

           Unbleached flour
    3/4 c  Sifted stone-ground whole

           Wheat flour
    1/2 c  Unsweetened cocoa powder

  1 1/2 ts Baking soda

    1/4 ts Salt (optional)

      1 c  Granulated sugar

    1/4 c  (plus 2 tablespoons lightly

           Packed brown sugar
      1    Medium baking potato, 4 oz.,

           Peeled and quartered
      1 pt Nonfat plain yogurt or

           Nonfat sour cream
      2 tb Mild honey

    1/4 ts Vanilla extract

    1/4 ts Chocolate flavor (optional)

    1/3 c  Canola oil

      3 lg Egg whites, at room temp

  Preheat oven to 350F.  Grease a 12-cup Bundt pan and dust with unsweetened
  cocoa powder.  Over a large bowl, sift both flours, cocoa powder, baking
  soda, and salt.  Mix in both sugars until there are no lumps.  Set aside.
  Put the peeled potato into a large food processor.  Using the steel blade,
  process the potato until finely minced.  Drain the yogurt of all excess
  liquid.  Discard excess liquid.  Add the drained yogurt, honey, vanilla,
  chocolate flavor, and vegetable oil to the minced potato in the food
  processor and mix on high for 60 seconds.  Be sure to scrape the sides of
  the bowl while processing.  Pour this mixture into the bowl of dry
  ingredients and beat with an electric beater on high for 60 seconds.  Be
  sure to scrape the sides of the bowl while beating.  Clean and dry the
  beaters well.
  In another bowl, beat the egg whites until soft peaks form.  Fold the egg
  whites into the batter until everything is mixed well.  Pour the batter
  into the prepared Bundt pan.  Bake in a preheated oven for 55 to 65
  minutes or until a cake tester comes out clean.  Remove the cake from the
  oven and let cool for 25 minutes.  Do not be concerned if the cake falls
  slightly.  Using a knife, go around inside and out side edges of cake.
  Invert the Bundt pan over a plate and carefully shake the cake loose.  Let
  the cake cool completely and frost with a chocolate glaze.