Preheat oven to 350 degrees.
Grease and flour one 13×9 cake pan.
In a large mixing bowl, cream the butter or margarine and sugar until light.
Beat eggs, one at a time, then add vanilla.
Sift together flour, baking powder, baking soda, salt, and cocoa powder.
Add to creamed mixture, alternating with water, and beating after each addition.
Stir in sauerkraut.
Pour batter into prepared pan.
Bake at 350 for 35 to 40 minutes.
Let cake cool in pan.
Frost with sour cream chocolate frosting (recipe below).
Cut into squares to serve.
