I decided to recreate this to the best of my ability. A couple of roommates lent a helping hand, so I must thank them for that.
Obviously, most of the mug contains cocoa (warm milk plus hot cocoa powder). Then there is a foundation of whipped cream. Into this layer is stuck a vanilla wafer cookie on the end of which resides a marshmallow toasted with my kitchen torch. Cover the entire thing with chocolate shavings et voila! This real-life version is not as pretty looking as the cartoon (especially since physics does not allow the wafer to stand on end in real life), but I think it looks good.