Famous Texas Fudge Cake

for cake:
1/2 cup cocoa powder
1 cup water
1 1/2 c (3 sticks) butter or margarine
3 cups all-purpose flour
3 cups sugar
1 1/2 tsp. baking soda
3/4 tsp. salt
3 large eggs
3/4 cup sour cream
1 1/2 tsp. vanilla

for icing:
1/2 cup (1 stick) butter or margarine
3/8 cup milk
1/4 cup cocoa powder
1 (1 pound box) powdered sugar
1 cup finely chopped nuts of your choice
1 1/2 tsp. vanilla

Preliminaries: Preheat oven to 350 degrees. Butter 9X13 in baking pan.

Prepare cake: Place 1/2 cup cocoa powder in medium saucepan; gradually stir in 1 cup water; bring to boil on medium high heat. Add butter and allow to melt. set aside.
Sift together onto wax paper the flour, sugar, baking soda and salt; add to hot mixture. Lightly beat eggs and add them to mixture along with sour cream and vanilla; stir thoroughly to combine.
Pour into prepared pan. Bake 30 minutes or until cake feels firm in center.
When cake is baked, prepare icing. In medium saucepan, combine butter or margarine, milk and cocoa; bring to a boil. Add powdered sugar and beat until smooth. Add chopped nuts and vanilla. Spread over hot cake. Cool before cutting.

(from: Chicken Soup for the Soul Cookbook)