Blend sugar and flour in a bowl, set aside.
In separate bowl, combine 1 stick butter, 1/2 C. vegetable oil, 4 TBSP cocoa,1 C. water.
Mix wet ingredients into flour/sugar mixture.
And sour cream, eggs, vanilla and baking soda. Mix well.
Pour into a large cookie sheet. Bake 20-25 minutes at 400°
In medium saucepan, mix 1 stick butter, 1/2 C. milk and 4 TBSP cocoa. Bring to a boil, reduce heat. Add 1 box (16 oz) powdered sugar and 1/2 C. nuts. Spread over cake.