In a medium bowl place the shortening, sugar, and eggs. Cream everything until the mixture is fluffy. Beat for 5 minutes more on high. In a medium bowl place the cocoa, flour, baking soda, and salt. Mix them together. In a small bowl place the vanilla and water. Alternately add a small amount of the flour mixture and then a small amount of the water mixture to the creamed egg mixture. Beat constantly until all of the ingredients are well mixed. Preheat oven to 350 degrees. Line the bottoms of 3 cake pans with waxed paper. Pour batter into greased and floured pans. Bake for 35-40 minutes. For frosting: In a medium bowl place the butter and cream it. In a small bowl place the cocoa and sugar and mix them together. In another small bowl place the milk and vanilla and mix them together. Alternately add a small amount of the cocoa mixture and then a small amount of the milk mixture to the butter, whipping constantly, until everything is well mixed.