Preheat oven to 350 degrees. Grease and flour a 9 by 13 inch pan. Mix flour, sugar and marshmallows in a large bowl. Heat and boil margarine, cocoa and cola in a saucepan. Remove from heat after it comes to a boil., pour over flour mixture. Mix together buttermilk and soda, add to mixture, add eggs. Mix well until everything is well blended. Pour into pan. Bake 30 to 35 minutes.
Make icing by heating together margarine, cocoa and cola, add nuts and confectioners sugar. Mix well. Pour over cake while still warm.
Not a NESTLÉ®-tested recipe.