Preheat the oven to 375F.

Separate egg yolks from egg whites. Place egg yolks in a large bowl, add powdered sugar and whip until the the mix nearly doubled or even tripled in volume. Keep whipping the egg yolks while slowly adding hazelnuts, bread crumbs and black coffee a little bit at a time.

Whip egg whites to firm peaks. Using a spatula, gently fold whipped egg whites to the egg yolk mix.

Turn the batter onto a 16 x 12 inch baking pan lined with parchment paper and spread evenly.

Bake at 375F for about 30-35 minutes. You may want to check for donness at 20-25 minutes with a toothpick.

Remove from the oven and let cool on a cooling rack without removing from the baking pan.

Now prepare the filling. Place sugar in a medium size pot, add espresso (or strong coffee), bring to boil and simmer over medium-low heat until the liquid thickens, about 10-12 minutes. Remove from the heat and let cool for about 3-5 minutes. The temperature should be no higher than 175F - 180F - use your candy thermometer to check the temperatures if you have one. Now slowly pour egg yolks into the syrup while constantly stirring. If the temperature is too high egg yolks will cook and turn into hard pieces. Start with a few drops first, if the syrup is too hot way a minute or so and try again. Once egg yolks are incorporated, add softened butter and beat until the cream is soft and airy.

Once the biscuit has cooled down, gently remove from the pan and cut in half. Spread the filling on top of each layer. Decorate with coffee beans and refrigerate overnight or longer. This cake gets better the more it is refrigerated. You can make it a day or two in advance.