Preheat the oven to 375°F. Heat chocolate with sugar and ¼cup water. This will take 5 to 6 minutes, with constant stirring. Heat and stir till a smooth syrup is formed.
In a mixing bowl whip butter with egg yolks till light and foamy. Add the chocolate syrup, ground walnuts and bread crumbs.
Adding salt and ice water, whip egg whites till so stiff a spoon will stand in them; then very, very gently fold them into the chocolate mixture.
Butter a 10-inch torte pan 3inches deep and sprinkle with flour. Shake out excess. Pour the batter into the pan, and bake in the preheated oven for 20 to 25 minutes. Cool the cake completely.
Make filling.
Cut the cooled torte into 2 layers. Fill the layers with two thirds of the filling. Use the rest as frosting. Finally, sprinkle with chopped walnuts. Serve chilled.