Lightly coat the bottom and sides of 2 10 inchx15 inch baking sheets with the melted butter. Line each sheet with parchment paper, then lightly coat the parchment paper with more melted butter. Set aside. Preheat the oven to 160ºC . In the top of a double boiler that is set over medium heat, place the remainder of the half pound butter and the 6- half oz. semisweet chocolate. Tightly cover with plastic wrap and allow to heat for 10-12 minutes. Remove from heat, uncover and stir until smooth. Hold at room temperature. Place the egg yolks and 1 cup sugar in the bowl of an electric mixer fitted with a paddle attachment. Beat on high until the mixture is lemon-colored and slightly thickened, about 4 minutes. Scrape down the sides of the bowl and beat on high for another 2 minutes. In another dry bowl,using the whip attachment, beat the egg whites until they are stiff but not dry. Using a rubber spatula, fold the chocolate mixture into the egg yolks. Add quarter of the egg white mixture into the chocolate mixture stirring to incorporate. Gently fold in the remaining egg whites until completely incorporated, with no white streaks remaining. Divide the mixture between the 2 prepared pans, smoothing the batter. Bake on the top and middle shelves in the oven for 20-22 minutes, rotating the sheets halfway through baking. Remove from oven and allow to cool for 30 minutes.
While the cakes are cooling, toast the hazelnuts on a baking sheet in the 350 degree oven for 10-15 minutes. (They will begin to give off a toasted scent when ready. Watch carefully, as they can burn easily.) Place the hot nuts in a large, clean kitchen towel and rub vigorously to skin. Allow the nuts to cool, then place them in a food processor and chop them to 0 cm size pieces. Invert 1 sheet of cake onto a large cutting board (larger than the pan). Place in the refrigerator for 30 minutes. Hold the remaining cake at room temperature until needed. To prepare the ganache, heat the heavy cream, 4 Tblsps. butter and quarter cup sugar in a medium sized, heavy saucepan, stirring to dissolve the sugar. Bring the mixture to a boil. Place 2 pounds of chocolate in a medium stainless steel bowl. Pour the boiling cream over the chocolate and allow to stand 6-7 minutes. Stir until smooth. Combine 3 cups ganache with the chopped hazelnuts. Hold this mixture at room temperature to use for filling. Remove 1 more cup of ganache and place it in a bowl in the refrigerator (to be used to decorate the diamonds). Keep the remaining ganache at room temperature until needed. To make the raspberry filling, puree the rasperries and 2 Tblsps. sugar in a food processor for 12-15 seconds. Strain the puree in a fine mesh sieve over a stainless steel bowl. Cover with plastic wrap and refrigerate unitl needed.
*ASSEMBLY*
Remove the cake from the refrigerator. Using a cake spatula, spread the raspberry puree over the cake, to the edges. Spread the hazelnut ganache over the raspberry filling, to the edges. Invert the other cake layer on top of the ganache covered layer. Remove the parchment paper from the second layer and press the layers together to hold them. Place the entire cake in the freezer for 1 hour. Remove the cake from the freezer. Using a very sharp serrated knife, cut away the uneven edges of the cake so it will measure 23 cm x 13- 1 cm. Use a serrated knife to cut the cake widthwise into 9 1- 1 cm strips. Trim a 3 cm, diagonally cut piece from each end of the strips, then cut the strip