Cream together the sugar, butter and cocoa; add well-beaten eggs, vanilla. Stir in flour and beat well. Add coconut and nutmeats, then spread in greased 9 x 13 inch pan. Bake 350 for 30-40 min
Take out of oven and spread small marshmallows and set back in oven just until marshmallows melt; remove and cool.
Frosting: Mix all ingredients together and spread on top of cooled marshmallows. Let set several hours before cutting.