Preheat oven to 350°. Cream together shortening and regular sugar until light. Blend in vanilla and chocolate. Add eggs, one at a time, blending well after each. Sift together flour, baking soda and salt. Add to creamed mixture alternately with sour milk; beat after each addition. Bake in 2 round greased and floured pans for 22 to 28 minutes. Toothpick should come out clean.

For the filling, combine whipped cream and confectioner's sugar. Slice cake layers in half to make 4 layers. Spread whipped cream mixture between each layer.

For icing: In small saucepan, combine butter, cocoa and milk and bring to a boil. Add one pound confectioners' sugar and vanilla. Beat until smooth and pour over assembled cake. Refrigerate.