Preheat the oven to 375 F (190 C).
Butter a 9-inch (23 cm) springform pan and line the bottom with parchment paper. Reserve.

Melt the chocolate in a double boiler, stirring until smooth. Remove the bowl and let cool.
Beat together the egg yolks and sugar in a bowl, until the mixture is thick and pale.
Combine the chocolate, hazelnuts, and Frangelico.

Beat the egg whites until stiff peaks form in another bowl, then fold into the chocolate mixture.
Pour the mixture into the prepared pan.
Bake for 45 minutes or until a toothpick inserted into the center of the cake comes out clean.
Let cool in the pan.
Just before serving, dust the top of the cake with confectioner’s sugar.