Preheat oven to 375. In a double boiler set over simmering water or in a saucepan over low heat, melt unsweetened and semi-sweet chocolate and butter, stirring frequently. Remove from heat.

Stir in salt, then vanilla, then sugar, then eggs, then flour, then walnuts, making sure each ingredient is incorporated before adding the next.

Lay out a sheet of aluminum foil. Drop spoonfuls of dough onto the sheet until all the dough is portioned out. Wet hands and roll each portion of dough into a 1 - 2 inch ball; arrange 2 inches apart on a parchment lined cookie sheet. Carefully press each ball with your hand or a fork to about 1/2 inch thick.

Bake for 10 to 12 minutes or until cookies feel soft but not wet when gently pressed down with your fingertips. Let cool on wire racks and then sift on a light topping of powdered sugar.