Sift flour and sugar together. Add marshmallows to the flour and sugar mixture. Set aside. Put butter, cocoa, and Dr Pepper in a saucepan. Heat until butter melts. Pour over sugar and flour mixture. Gently stir together. In a separate bowl, mix eggs, buttermilk, and baking soda. Add to first mixture. Bake 45 mins at 300 degrees in a bundt pan. Remove from the oven and let cool completely in pan. (If you don’t cool it completely, it will crumble). Cover with icing.

Boil butter, cocoa, and Dr Pepper until the butter melts. Add sifted sugar and nuts. Drizzle over cake.