Mix flour, sugar, & salt in bowl set aside. Mix and boil in pan margarine, oil, water and cocoa. Add flour mixture. Dissolve baking soda in buttermilk then add to mixture. Beat eggs well then add to mixture with vanilla. Pour into greased 18x12x1 cookie sheet.
Bake at 350°F for 20 minutes - no longer.
Boil margarine and milk until it bubbles. Then add powdered sugar, cocoa, vanilla and nuts. When cool, ice cake.