1. Preheat oven to 350°F (176°C) and line cupcake pan with cupcake liners.
2. Combine flour, baking soda and salt in a medium-sized bowl. Set aside.
3. Add water, cocoa powder and vanilla extract to another medium-sized bowl and combine. Mixture will be thick. Set aside.
4. In a large mixer bowl, cream the butter and sugar until light in color and fluffy, about 3-4 minutes.
5. Add the eggs one at a time, beating until combined.
6. Add chocolate mixture to batter and mix until well combined. Scrape down the sides of the bowl as needed to make sure everything is combined.
7. Alternate adding the flour mixture and milk to the batter. Begin by adding half of the dry mix, then mix well. Add the milk and mix well, scraping down the sides as needed. Add the remaining flour mixture and mix until smooth.
8. Fill cupcake liners about 3/4 way. Bake for 15-17 minutes, or until a toothpick inserted comes out with a few crumbs.
9. Allow cupcakes to cool about 2-3 minutes, then remove to a cooling rack to finish cooling.
10. To make the frosting, combine the butter and shortening in a large bowl and mix until smooth.
11. Add the Nutella and mix until well combined and smooth.
12. Add half of the powdered sugar and mix until smooth.
13. Add about half of the milk and mix until smooth.
14. Add remaining powdered sugar and mix until smooth.
15. Add remaining milk as needed and mix until smooth, keeping an eye on the consistency of the frosting so it doesn’t get too thin.
16. When the cupcakes have cooled, use a cupcake corer to remove the centers.
17. Fill the centers of the cupcakes with Nutella, then pipe the Nutella frosting onto the cupcakes. I use Ateco tip 808.
18. To make the Nutella drizzle, combine the Nutella and whipping cream.
19. Drizzle the mixture over the cupcakes, the sprinkle with hazelnut crumbs, if desired.