1. Prepare four 8 inch cake pans with parchment paper circles in the bottom, and grease the sides.
2. Add all dry ingredients to a large bowl and whisk together.
3. Add eggs, buttermilk and vegetable oil to the dry ingredients and mix well.
4. Add vanilla to boiling water and add to mixture. Mix well.
5. Pour into four 8 inch cakes pans and bake at 300 degrees for about 25 minutes, or until a toothpick comes out with a few crumbs. I baked the cakes in two batches, two at a time, with about 1 1/2 cups of batter per pan.
6. Remove cakes from oven and allow to cool for about 10 minutes, then remove to cooling racks to cool completely.
7. Make icing while cakes cool. Beat together butter and shortening until smooth.
8. Add Nutella and mix until smooth.
9. Slowly add half of the powdered sugar and mix until smooth.
10. Add 2-3 tbsp of milk or water and mix until smooth.
11. Slowly add the remaining powdered sugar and mix until smooth.
12. Add more water or milk until the frosting is the right consistency.
14. Place first layer of cake on a plate or cardboard cake circle. Add about 3/4 cup of frosting and spread into an even layer.
15. Add second layer of cake and add another 3/4 cup of frosting and spread into an even layer.
16. Add third layer of cake on top and add another 3/4 cup of frosting and spread into an even layer.
18. To make the chocolate ganache, place the chocolate chips in a medium sized bowl.
19. Microwave the heavy whipping cream just until it starts to boil. Pour over the chocolate chips and let sit for 2-3 minutes, then whisk until smooth (see my tips on making chocolate ganache
20. Drizzle the chocolate ganache around the edge of the cake, then pour the remainder of the ganache on top of the cake and spread evenly. I like to use a squeeze bottle
for drizzling around the edges. See my tips for making a chocolate drip cake
21. Allow the ganache to firm up a bit, then pipe the remainder of the frosting around the top edge of the cake and top each swirl with a Ferrero Rocher candy. I used Ateco tip 849
22. Cake is best when well covered for 3-4 days.