Preheat oven to 300°F (148°C). Prepare three 8-inch cake pans with parchment paper circles in the bottom, and grease the sides.

In a large bowl, whisk together the flour, sugar, cocoa powder, baking soda, and salt until evenly combined.

Add the eggs, milk, vegetable oil, and vanilla extract. Mix with an electric mixer until smooth and well blended.

Gradually pour in the hot water and stir gently on low speed until fully incorporated. The batter will be very thin—this is normal.

Divide the batter evenly among the three prepared cake pans. Bake for 30-33 minutes, or until a toothpick inserted comes out with a few moist crumbs.

Remove cakes from oven and let cool in pans for 10 minutes. Transfer to wire racks, remove parchment, and let cool completely.

In a large bowl, beat the room temperature butter and 280g Nutella on medium speed until smooth and fluffy, about 3 minutes.

Add half of the powdered sugar and mix on low. Once incorporated, increase speed to medium and beat until smooth.

Add 5-6 tablespoons of heavy cream gradually, then add the remaining powdered sugar. Beat until creamy. Adjust cream for desired consistency.

Level the cooled cake layers using a serrated knife. Place the first layer on a cake stand and spread about 1 cup of buttercream evenly on top.

Add the second cake layer and spread another 1 cup of buttercream. Place the third layer on top, upside down for a flat surface.

Apply a thin crumb coat over the entire cake and chill for 20 minutes. Then apply a full, even layer of Nutella buttercream.

For the ganache: Combine Nutella, chocolate chips, and heavy cream in a bowl. Microwave in 15-second intervals, stirring between each, until smooth and pourable.

Drizzle the ganache around the edges of the cake for a drip effect. Then pour the remainder on top and spread evenly.

Allow ganache to set for 20 minutes. Using a piping bag fitted with Ateco tip 844, pipe buttercream swirls around the top edge, placing a Ferrero Rocher in between each swirl.

Store cake in an airtight container. It can be kept at room temperature for up to 24 hours, then refrigerate. Bring to room temperature before serving.