Preheat your oven to 350 degrees/F and prepare 3 8-inch cake pans by rubbing generously with vegetable shortening and dust with unsweetened cocoa powder.

In the bowl of a stand mixer equipped with a whisk attachment, add the flour, sugar, cocoa powder, baking powder, baking soda, salt, and espresso powder and whisk until well combined.

Add in the vanilla, eggs, milk, and vegetable oil and mix until there are no dry spots remaining.

Add in the boiling water last and mix on low speed. Slowly increase to high for 1-2 minutes.

Divide the batter evenly between the three cake tins and bake for 25-30 minutes or until a toothpick inserted in the center of each cake comes out clean.

Remove from the oven and allow the cakes to cool completely on a wire rack.

In the bowl of a stand mixer equipped with a paddle attachment, cream the butter on high speed for 4-5 minutes until fluffy.

Add the Nutella and mix until just combined. Scrape the sides and bottom of the bowl .

Add half of the powdered sugar and mix on low speed until combined. Add the remaining powdered sugar and mix until there are no dry spots remaining.

Slowly pour in the heavy cream and vanilla extract. Mix on low speed until combined then slowly increase the speed to high for 4-5 minutes. Don't skimp on the creaming time. Mix until you have a fluffy, spreadable consistency.

If needed, use a large serrated knife to remove the domes off of the cake layers.

Place one cake layer face down on a serving tray or cake stand and top with about 1 1/2 cups frosting and smooth. Top with about 1/4 cup crushed hazelnuts and gently press into the frosting. Repeat with the remaining cake layers.

Once you place the last cake layer on, smooth a thin layer of frosting all over the cake sealing in the crumbs. Refrigerate for 15-20 minutes.

Remove from the refrigerator and cover the cake in the remaining buttercream, reserve about 1 cup of frosting if you want to pipe swirls on the top of the cake.

Add the remaining frosting to a piping bag with a Wilton 1M tip and pipe swirls around the top of the cake. Top each swirl with half of a Ferrero Rocher chocolate. Sprinkle with crushed hazelnuts if desired.

Refrigerate until ready to serve.

Keep the cake stored in an air tight container for up to three days.