Grandma Gneiting's Zucchini Brownies

1 ½ c sugar
½ c vegetable oil
¼ c cocoa
2 c shredded zucchini
2 c flour
1 ½ tsp baking soda
1 tsp salt
2 tsp vanilla
2 eggs
1 c chopped nuts
Spread in greased and floured cookie sheet. Bake at 350 F for 20-25 minutes. Cool and spread on icing.
Icing:
1 cube butter
4 T cocoa
5-6 T buttermilk (can use milk with a few drops of vinegar)
Bring to a boil. Then add:
1-1 ½ lbs powdered sugar
1 tsp vanilla