Good heavens did I used to love Nutella. It is delicious, sweet chocolaty goodness. It also is made with milk, and I can't have it.
I have found a substitute that, in some ways, I actually like better!
Justin's Chocolate Hazelnut Butter (website here) is really good. It isn't as sweet as Nutella, and is a bit coarser, and these are things that I like. It tastes distinctly like chocolate and hazelnuts. It is a little pricey, but for a tasty GF/DF/vegan product, that's ok. I will most definitely be buying a jar of this soon.
Disclaimer: neither Nutella or Justin's knows who I am. I just like to eat their products.