Melt the dark chocolate in a bain-marie and cover the half walnuts with the chocolate. Later, lay them on a tray on which you lay greaseproof paper and leave to rest in the freezer. Separate the whites and yolks of the eggs.

Put the butter and powdered sugar in a bowl and whisk. Add the egg yolks and continue whisking. Add chopped walnuts and milk. Add flour and baking powder

Add the chocolate covered walnuts that you keep in the fridge. Whisk the egg whites until they turn into snow and add to the mixture.

Pour the mixture you have prepared into a cake mold with a hole in the middle and bake it in a preheated 175 degree oven for 60 minutes. Pour the bitter chocolate melted in a double boiler over the warm cake. Garnish with walnuts and serve.