• Butter a 9-inch spring form, then line with parchment paper and butter parchment paper. Wrap spring form with a few layers of aluminum foil.

Make the Cake

• Combine water and sugar and bring to a boil. Dissolve the sugar and simmer for a few minutes.
• Melt the butter, and chop the chocolate. Add the chocolate and stir until smooth. Add the syrup (water/sugar solution) and mix with the chocolate. Allow to cool a little.
• Whisk the eggs slightly and add to the chocolate mix and stir until well blended.
• Pour mix into the spring form. Place spring form in a large pot or roasting pan, add water until the level of the cake batter.
• Bake cake in the oven for approx. 50-55 minutes. The center of the cake should no longer jiggle.
• Remove cake from pan (leave in spring form) and cool on rack.

Make the Ganache

• Chop the chocolate. Bring whipping cream to a simmer and add the chocolate and stir until smooth.
• Poor the mix over the cake, while still in the spring form. Refrigerate cake overnight.

Prepare the Hazelnut Crust

• To peel the hazelnuts for the hazelnut crust: bring 2 cups of water to a boil and add the baking soda. Add the hazelnuts and boil for approx. 3 minutes. Be aware that this is going to become a foamy business, so use a high saucepan, otherwise it will foam over. The water will also turn purple black.
• After about 3 minutes remove the hazelnuts from the pan and place them into a bowl with ice water. Remove the skin with your fingers. Place nuts on a kitchen towel and dry them. Once dried, place them on a baking dish and toast them for 15 minutes in the oven. Cool and place them in the food processor and pulse until they become course or finer pieces of nuts. I kept them rather course avoiding the hazelnuts to turn to dust.

Final Touches

• Run knife around the sides of the spring form and un-clamp the ring. Open the ring a little bit and check to be sure it has come away cleanly from the sides.
• Remove the cake from the bottom and place on flat dish. Use your hands and press the hazelnut pieces into the sides of the cake.