Put chocolate and butter in a pot and melt it on low heat. Stir and make sure it doesn’t start to boil.
When it is melted, add in sugar and check that the mixture is not too hot (wait and cool it down if it is), because now you need to whisk in eggs, one by one. Also add in vanilla aroma.
Put flour, salt, cocoa powder and ground walnuts in a bowl and stir then add it to the chocolate mixture while whisking. And also stir in 50 grams of chopped walnuts.
Pour the batter in baking tray with baking paper. I used baking tray size 36 x 21,5 cm.Sprinkle on top with remained chopped walnuts.
Bake it in a preheated oven on 180 degrees Celsius for 35 minutes. Take it out of the oven and leave to cool down, then slice and serve.