How can something so good be so easy? I don't know, but it is.
Ingredients
2 C Milk
1/2 C Nutella
Make all the other versions first, because you want to save the best for last and the one with Nutella in it is obviously going to be the best.
I actually looked up a recipe for this and I found one from Martha Stewart. It's dead simple: whisk the milk and the nutella together in a saucepan while you bring it to a simmer. That's it. Hers called for a cup and a half of milk and a third of a cup of Nutella. I did that originally, and then decided that it wasn't going to make enough, so I just started adding milk and Nutella until it looked right. I probably landed closer to the proportions in the list above. The real lesson here is that you probably can't use too much Nutella.
It takes a lot of whisking, but eventually, the glob of Nutella will break down. It settles pretty easily, though, so make sure you stir it really well before serving.
I don't know. Like I said, it was dead simple. Milk, Nutella, heat, stir. Eventually, you have hot cocoa!