Finely grate a bar of chocolate, mix the chocolate pudding with 1/8 liter of milk, do not boil.
Mix eggs, butter and sugar until foamy, alternately stir in flour (sifted and mixed with baking powder), grated chocolate and custard milk into the egg mixture. When everything is well mixed, fold in the hazelnuts and pour into a loaf pan.
Bake at 180 degrees for 70 minutes (convection oven 60 minutes). Turn the cake out onto a wire rack and let it cool down.
Melt the rest of the chocolate over a bain-marie and spread it over the cake (I love the children to spread 1 1/2 bars of Milka).