I just ran across this message on altonbrown.com:

Pendragon's Cocoa Potato Cake
Submitted by and thanks to Pendragon MM Crowley
(Your friends won't know until you tell 'em!)

1/2 cup (1 stick) butter, softened
2 cups white sugar
3 eggs, seperated
1 cup hot mashed potatoes (instant is fine, just as long as it's already
made)
1/2 cup cocoa powder
2 cups all-purpose flour
2 teaspoons baking powder
a dash of ground cinnamon
1/2 cup milk
1 teaspoon vanilla extract
1/2 half cup chopped nuts (almonds'r nice)

Tools:
Standard cake pan, 13x9x2
Upright mixer
Stick blender (mwahahaha)
2 additional small bowls

Preheat the oven to about 350 deg F. Grease and flour (with cocoa powder)
the pan, and set it aside. In the mixer, cream the butter and sugar. Add the
egg *yolks*, one at a time, waiting for each to be fully incorporated.
Gradually add your mashed potatoes until they are very well blended
together. Combine your dry ingredients (flour, cocoa, baking powder, and
cinnamon) in one of your bowls and alternate pouring that and your milk to
the butter compound in the mixer. When you're finished, add the vanilla
extract and your nuts. No, I'm not referring to your mental state (though
some might, if they knew the recipe name), I'm referring to the seeds being
added into the mixture. Right, now with a stick blender (refer to the
earlier maniacal laugh) whip you egg *whites* to stiff pearly peaks. Fold
this gently into the mix, to add a bit of variety in its texture. Pour all
of this into your patiently waiting 13x9x2, and into the oven she goes. 35 -
40 minutes later (depending on altitude) your cake will be complete. Since
we're playing in Mr. B's sandbox, we'll go by his rules: skip the toothpick
and go with the "bounce" test he used for his cornbread in "Ear Apparent".
If it rises from a touch of a (gloved) hand, it's done. Let rest on a wire
rack, frost with the good stuff, and fool your friends!

"We've replaced the flour in our recipe with mashed potatoes. Let's see if
he can taste the difference..."


Bob