In a bowl mix the flour, cocoa and salt and confused. In another large bowl, break the butter and sugar until smooth (about 2-3 minutes). Add vanilla and egg yolks. Add flour mixture, stirring until all ingredients are mixed well. Shortbread is pressed well into an oiled form (20-23 cm) using an inverted spoon. Bake in preheated oven (180 C) 20-25 minutes or just until cake is no longer looks wet and is firm to the touch. Meanwhile melted chocolate and the butter in a water bath. Hot cake pour hot chocolate, smoothed out evenly distributes the glaze (1 cm). Sprinkle with chopped nuts that are pressed lightly glaze. After cooling completely cut. It can be stored in a container at room temperature for several days.