Chocolate and marshmallow -- nature's perfect food combination! Add a graham-cracker sponge cake and you get a taste of s'mores, the childhood treat. The original, which was from the amazing cookbook called In the Sweet Kitchen,included a homemade marshmallow filling that was very fragile, and spread on the outside. I used fluff from a jar and spread it inside the cake roll because any marshmallow is a good marshmallow. The marshmallow oozes out once the cake is cut, so serve it all at once for the best presentation. I wish one of you kitchen wizards could figure out a way to prevent the ooze.