Place 5 eggs into the bowl of a stand mixer. Beat the eggs on high speed with the whisk attachment for about 4 minutes.
Add 2 cups sugar to the eggs and continue beating on high speed for an additional 4 minutes.
Add the 1 tsp vanilla and 1 cup buttermilk to the eggs. Beat again just until incorporated.
Dissolve 2 tbsp instant espresso powder with 1 cup room temperature water. Then add it to the cake batter. Then add in the melted butter.
Sift, 2 1/2 cups flour, 1 tsp salt, 1 1/2 tsp baking soda, 1 tsp baking powder, and 1 cup dutched cocoa powder into the egg mixture. Then gently fold the dry ingredients into egg mixture using a whisk.
Split the cake batter amongst 3 (9 inch) cake pans. Bake at 350 degrees for 15-20 minutes or until a toothpick comes out clean when inserted into the center of the cake.
Meanwhile beat 16 oz softened cream cheese, 2 cups softened butter, 1/2 cup cocoa powder, 2 1/2 cup powdered sugar, 1/2 tsp salt, and 2 cups Nutella.
Once the cakes are baked flip them onto cooling racks and let them cool completely. If you want your cake to have a flat top, use a serrated knife to slice the top of each cake.
Assemble the cake by frosting the top of each cake layer. Once the last cake layer is placed, Frost the top and sides of the cake.