preheat oven to 350.

in a bowl' sift the sugar and flour

add marshnallows

in saucepan, mix the butter, oil, cocoa and coca cola. bring to a boil and pour over dry ingredients, blend well.

dissolve baking soda in buttermilk just before adding to batter along with eggs and vanilla extract, mixing well

pour into greased 9x13 inch pan and bake 35to 45 minutes. remove from oven immediately.

to make frosting combine butter, cocoa, and cola cola in a saucepan. bring to a boil and add confection sugar blending well.add vanilla extract and pecans. spread over hot cake. when cooled cut into squares and serve.