The "nut-shell" version of the story? The spread was first developed by Italian, Pietro Ferrero during WWII when cocoa was being rationed. First called "Supercrema Gianduja" it was made from hazelnuts, that were on hand, and cocoa. The story went on to explain that children would go to the store with bread to get a "shmear" so to speak.
3/4 C milk
2 heaping T Nutella
Heat the milk in the microwave for 2 minutes or in a saucepan until warm. Stir in the Nutella. If you're using the microwave put it back in for another minute and stir. Top with whipped cream.
I will have to try this again with the whipped cream, but it was good without it. One to keep in mind for a snow day!
Recipe Source: Hot Chocolate by Michael Turback, pg. 95, Nutella Hot Chocolate by Chuck Silverston, Paris Creperie