For the cake, using a stand mixer or hand mixer, cream together butter and sugar. Gradually add Silver Fleece Sauerkraut, followed by eggs and vanilla, mixing constantly.
In a separate bowl, sift together flour, cocoa, baking powder, and baking soda. Alternate gradually adding flour mixture and water to sauerkraut mixture, mixing constantly.
Add cake batter to a greased 9x13 baking dish. Bake for 35-40 minutes and allow to cool.
For frosting, in a small sauce pot, melt chocolate chips and butter over low heat, stirring occasionally. Remove from heat and add sour cream, vanilla and salt. Mix well. Gradually add powdered sugar and combine to desired consistency. Frost cooled cake.