How to cook
Put 2.1 oz (60 g) of butter, 3 tablespoons of milk and 2.8 oz (80 g) of brown sugar in a small pot. Heat the products, until the sugar melts.
Line a detachable cake tin 9.5″ (24 cm) with baking paper. Pour the mixture, level it out and spread the coarsely chopped walnuts evenly.
Refrigerate the cake tin, until you make the sponge cake mix. Put the remaining butter and sugar in a bowl.
Beat with a mixer, until a homogeneous mixture is obtained. Add the eggs one after the other, by beating with the mixer, until they are completely absorbed. In another bowl, mix the flour with the baking powder, cocoa and a pinch of salt. Add it to the butter cream.
Melt the chocolate in a water bath. Pour it in a thin stream into the mixture and homogenize it. Remove the cake tin from the fridge and pour the cake mixture in it. Level it out.
Bake the cake in a preheated oven at 340°F (170°C) with a fan for about 35-40 minutes.
Wait for the baked cake to cool completely and carefully turn it over onto a suitable plate.