Melt half of the sugar (1/2 cup) to caramelize and add half the hazelnuts (1/2 cup). Combine the sugar with the hazelnuts well and set aside to cool.In another bowl with a mixer, whisk the eggs and the rest of the sugar until you get a nice foamy structure.Melt the butter or coconut oil in a pot and combine it with the egg mixture. Add the melted chocolate and the rest of the hazelnuts to the mixture.Finely chop the caramel and hazelnuts and add them to the mixture. Finally add the crushed whole grain biscuits and mix well together.Pour the contents into a triangular mold and put it in the fridge for about 2-3 hours to harden.