Preheat oven to 350 degrees F.

Butter and flour a 9x13 baking dish.

Melt together the butter, 8 oz. of chocolate chips, and the unsweetened chocolate in a medium bowl over simmering water. Allow to cool slightly. In a large bowl, stir (do not beat) together the eggs, vanilla, and sugar. Stir the warm chocolate mixture into the egg mixture and allow to cool to room temperature.

In a medium bowl, sift together 1/2 & 1/8 cup of flour, the baking powder, and salt. Add to the cooled chocolate mixture. Add the walnuts and 6 ounces of chocolate chips to the chocolate batter. Pour into the baking dish.

Bake for about 25 minutes. Do not overbake!