Special equipment: Springform cake pan
Preheat the oven to 400 degrees F.
In a large bowl combine the ground hazelnuts, egg yolks, vanilla, sugar, and cinnamon. In a separate bowl beat egg the whites until stiff peaks form. Add 1/4 of egg white mixture to the hazelnut mixture and incorporate. Add the remaining egg whites and fold together until no streaks are left from the egg whites, taking care not to deflate the egg whites. Pour the mixture into a nonstick springform cake pan and bake until a fork comes out clean when inserted in the center of the cake, about 50 minutes. Remove the cake from the oven, let cool slightly and release the sides. To serve, slice the cake and top with chocolate mousse and berries, or whipped cream, if desired.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.