Chocolate Potato Cake

Ingredients: One medium (5oz.) potato raw w/o skin, One and three quarters cups of cake flour, Three quarter cup of cocoa, Two large eggs, One teaspoon of vanilla extract, Two cups of sour cream, One and three quarters cup of of sugar, One half cup of ,unsalted butter, One and one half teaspoons of baking soda, One half teaspoon of salt, Three and one half cups of chocolate sour cream frosting.

Preparation: Preheat oven to 350degrees. Butter and lightly flour a 13x9 inch cake pan. In the food processor, shred potato with shredding disc. Remove disc and replace with blade. Add half of all the remaining ingredients with the exception of the frosting and mix for three minutes, stopping once to scrape down the sides of mixing container. Transfer potato batter to a large bowl, do not clean container. Add all remaining ingredients, again with the exception of the frosting, to the processor and mix for three additional minutes, again stopping to scrape down sides of container. Add contents of the food processor to the potato batter, mixing well. Transfer batter to prepared cake pan. Bake 35-40 minutes or until tester comes out clean. Cool completely on wire rack. Frost with sour cream frosting. 

Ingredients(Frosting): One half cup of butter, Four and one half cups of confectioner sugar, Three quarter cup of sour cream, One half cup of margarine, Eight ounces of semi sweet chocolate chips, One tablespoon of vanilla extract.

Preparation: Melt and cool chocolate chips in double boiler. Cream butter and margarine. Add sugar and beat until light and fluffy. Add cooled chocolate, sour cream and vanilla. Beat until light and creamy.