Preheat oven to 300 degrees.
Grease and flour pans and sift flour and sugar.
In saucepan, mix water, shortening, butter, vanilla, and cocoa and bring to a boil (stir often).
Pour over flour/sugar mixture.
Mix eggs, baking soda, and buttermilk together in a separate bowl and add to chocolate mixture.
Pour into greased and floured 13 x 9 x 2-inch pan.
Bake at 400 degrees for approximately 25 minutes.
Make frosting:In a saucepan, combine sweet milk, cocoa, and butter and bring to a boil.
Add 1 box powdered sugar and vanilla gradually; mix well.
Add pecans and mix with icing.
Pour and spread over hot cake.