Bake raw hazelnuts and walnuts in a tray for a few minutes until they release their aroma. Pour them quickly in a cold plate and let them cool completely. With a cloth, rub them, to scrape their shells off. Blend or puree the nuts, sugar and vanilla sugar into a fine mass.
Subsequently, mix the cocoa into the mixture. Heat the cream in a pot on the stove and add the crushed chocolate. Stir until completely dissolved. Leave chocolate mixture to cool slightly and then stir it into the mixture with nuts and cocoa.
Stir frequently, then leave to cool completely. Transfer to a suitable container or jar and store in the refrigerator.