Preheat oven to 180°C.

Melt the chocolate in a bowl over a pot of simmering water.

In another bowl, beat the eggs and sugar using a electric whisk(mixer) for about 8 minutes until thick.

Pour the melted chocolate into the egg-sugur mixture, and add the melted butter and stir well.

Sift in the flour and salt, and add the butter. Stir well. Finially add the chopped walnuts. Pour batter into a baking tray lined with baking paper.

Bake in the preheated oven for about 40 minutes or until a tooth pick.inserted in the middle comes out clean. Let it cool and cut it into pieces. Sprinkle with icing sugar and serve. :)