Triple Chocolate Brownies

6 oz bittersweet chocolate, chopped (I use Ghirardelli 60% bittersweet chips)

2 oz unsweetened chocolate, chopped

12 tablespoons (1 1/2 sticks) unsalted butter

1 1/2 cups (10 oz) sugar

2 teaspoons vanilla extract

4 large eggs

1 cup (5 oz) all-purpose flour

1 teaspoon salt

1 cup semi-sweet chocolate chips

3/4 cup chopped walnuts, pecans or almonds (optional)

Butter and flour a 13" x 9" pan and set aside. In a metal bowl, combine the butter, bittersweet and unsweetened chocolates and set it over a pan of simmering water. Stir until the chocolates and butter are melted and combined, then remove from the heat. Let the mixture cool until it is lukewarm, then stir in the sugar and the vanilla. Add the eggs one at a time, stirring until incorporated. Add the flour and the salt, stirring until just combined (a few flecks of flour are OK), then mix in the semi-sweet chips. Spread in the prepared pan, smooth the top and scatter the nuts over the top, pressing very lightly. Bake at 350 for 25-30 minutes, until a tester comes out with crumbs adhering to it. Cool completely before cutting.