Mix flour and sugar. Heat butter, cocoa and cola to boiling and pour over flour and sugar. In separate bowl mix buttermilk, eggs, soda, vanilla, and marshmellows. Add to flour mixture and mix well. Batter will be thin. Bake in 13 x 23 cm pan at 180ºC or 30-35 minutes. Ice while hot with the following: Heat butter, cocoa and cola to a boil. Pour over sugar and wix well. Add nuts . Ice cake while both cake and icing are hot. ----