for the Cake :
Mix flour and sugar in a large bowl. In a medium saucepan, combine butter, water, and cocoa over medium heat.
Bring mixture to a boil and pour over the flour/sugar mixture. Mix well. Add eggs, buttermilk, baking soda, and vanilla.
Pour into a well-greased 9×13 pan, and bake at 350 for 30 minutes.
for the fudge icing
In a medium saucepan, combine butter, milk, and cocoa and bring mixture to a boil.
Remove from heat and add powdered sugar, stirring well with a whisk or wooden spoon until the sugar melts and the mixture is smooth.
Stir in vanilla and pecans, then pour over hot cake.