Make the Cakes

1. Preheat oven to 300°F (148°C). Prepare three 8-inch cake pans with parchment paper circles in the bottom, and grease the sides.
2. Add flour, sugar, cocoa powder, baking soda and salt to a large bowl and whisk together.
3. Add the eggs, milk, vegetable oil and vanilla extract to the dry ingredients and mix until well combined.
4. Add the hot water and gently mix until well combined. The batter will be very thin.
5. Divide batter evenly between cakes pans and bake for 30-33 minutes, or until a toothpick comes out with a few crumbs.
6. Remove cakes from oven and allow to cool for about 10 minutes, then remove to cooling racks to cool completely.

Make the Buttercream

1. To make the buttercream, beat the butter and Nutella until well combined and smooth.
2. Add half of the powdered sugar and mix until well combined and smooth.
3. Add 3 tablespoons of heavy cream and mix until well combined and smooth.
4. Add the remaining powdered sugar and mix until well combined smooth. Add additional heavy cream, as needed to get the right consistency of frosting.

Assemble the Cake

1. To put the cake together, use a large serrated knife to remove the domes from the top of the cakes so that they’re flat. These cakes don’t have a large dome, but I like to make sure they’re completely flat. See my tips on how to level a cake.
2. Place the first cake on a serving plate or a cardboard cake round. Spread about 1 cup of buttercream evenly on top of the cake.
3. Add the second layer of cake and another cup of buttercream.
4. Top the cake with the remaining layer and frost the outside of the cake. Refer to my tutorial for frosting a smooth cake, if needed.
5. To make the Nutella ganache, add the Nutella, chocolate chips and heavy whipping cream to a medium sized bowl. Heat in 15-20 second increments, stirring well between each, until the mixture is melted and smooth.
6. 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 on making a chocolate drip cake.
7. Allow the ganache to firm up a bit, then pipe the remainder of the frosting around the top edge of the cake, alternating swirls of buttercream with the Ferrero Rocher candies. I used Ateco tip 844.
8. Store cake in an air-tight container. It should be fine at room temperature for up to 24 hours, then should be refrigerated. Serve at room temperature or only slightly cool, not cold. The cake is best if eaten within 4-5 days.