Preheat the oven to 350°F. Grease a 9 x 9-inch pan, line with paper and grease the paper.
Melt the chocolate and butter together. Beat the eggs with the sugar until fluffy and add to the chocolate mixture.
Add the flour, blend and add the nuts, vanilla and salt. Stir until well mixed.
Spread batter in prepared pan. If desired, garnish top with additional walnut or pecan halves. Bake for about 25 minutes. Cool in pan, turn out, remove paper and cut into squares or bars.