Preheat oven to 350F. Mix flour, 2 cups sugar, cinnamon, and marshmallows. Melt and bring to a boil margarine, shortening, 2 tablespoons cocoa and Coca Cola. Pour over first mixture. Beat eggs. Add soda and buttermilk. Mix all mixtures together. Pour into greased jelly roll pan and bake at 350F for 30 minutes.
To prepare icing:
Combine margarine, 1-1/2 cups sugar, milk, and 3 tablespoons cocoa. Bring to a rolling boil. Continue to boil for 1 minute. Add powdered sugar. Beat thoroughly. Add pecans. Pour over hot cake.
Cajun Country -- New Iberia, Louisiana