How to make
Melt the butter over low heat and stir with a mixer along with the sugar and 4 eggs. Mix until the sugar is completely melted.
Excluding the chocolate and walnuts, mix the remaining ingredients together in a separate bowl. Add the resulting mixture to the butter mixture and stir until it all becomes homogeneous. Crumble the chocolate and walnuts into pieces and add them to the mixture. Put the mixture into a buttered baking dish.
Place in a preheated 300°F (150 °C) oven and bake for 40 minutes. Allow the cake to cool slightly and then cut it into cubes. To decorate, you can put chocolate chips or powdered sugar on top.