Here's the recipe but if it's not exactly the one you're looking for go to
http://www.cooks.com and they have loads of recipes for it.
COKE CAKE
2 c. cake flour (unsifted)
1 c. butter
1 c. Coke
2 beaten eggs
1 1/2 c. miniature marshmallows
2 c. sugar
3 tbsp. cocoa
1/2 c. buttermilk
1 tsp. vanilla
1 tsp. baking soda
Combine flour and sugar in mixing bowl. Heat butter, cocoa and Coke to boiling and pour over flour and sugar mixture and mix thoroughly. Add buttermilk, eggs, soda, vanilla and marshmallows, mix well. This will be a thin batter with marshmallows on top. Pour into a greased 13 x 9 inch pan and bake at 350 degrees for approx. 45 minutes or until done. After baked, ice while hot.
FROSTING:
1/2 c. butter
3 tbsp. cocoa
1/2 c. Coke
1 lb. 10x sugar
1 c. chopped pecans
Heat butter, cocoa and Coke to boiling. Pour over 1 pound confectioners' sugar and mix well. Add chopped nuts. Spread over hot cake.