Preheat oven to 375 degrees F. Grease and flour 17 x 12 sheet pan.
In a large bowl sift together sugar, flour and salt, set aside.
In a heavy pan, heat over medium-low heat butter, water and cocoa until butter is melted, stirring constantly; remove from heat; add immediately to flour mixture; blend well with wooden spoon. In a small bowl crack eggs, add in sour cream or buttermilk, vanilla and soda, mixing well. Blend well into cake mixture. Pour into prepared pan and smooth top. Bake for 20 to 25 minutes.
Prepare frosting when cake is almost done baking.
Butter Nut Frosting
˝ cup butter or margarine
2 cups powdered sugar, heaping (measure then sift)
4 Tbsp. whole milk, cream or canned milk
3 Tbsp. cocoa, heaping
1 tsp. vanilla
1 cup chopped pecans, walnuts or almonds, optional
In heavy sauce pan melt butter with cocoa; add milk and cook for 1 minute longer, remover from heat; mix in the powdered sugar, vanilla and pecans, until frosting is smooth.