Preheat oven to 350 degrees. In a bowl, sift sugar and flour. Add marsh- mallows. In
saucepan, mix 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 a well-greased 9-
by-13-inch pan and bake 35 to 45 minutes. Remove from oven and frost
To make frosting, combine butter, cocoa and Coca-Cola in a saucepan. Bring to a
boil and pour over confectioners' sugar, blending well. Add vanilla extract and
pecans. Spread over hot cake. When cool, cut into squares and serve.