1 pound unsalted butter
1 pound plus 3 cups semisweet chocolate chips
6 ounces unsweetened chocolate
6 large eggs
2 tablespoons plus 1 1/2 teaspoons powdered instant espresso
2 tablespoons vanilla extract
2 1/4 cups granulated sugar
1 cup sifted all-purpose flour
1 tablespoon baking powder
1 teaspoon salt
3 cups chopped walnut pieces

Preheat oven to 350 degrees F. Grease and flour an 18 x 12-inch jellyroll pan. Set aside.

Melt together the butter, 1 pound of chocolate chips and unsweetened chocolate until smooth in the top of a double broiler. Cool to room temperature.

Combine, but do not whisk, eggs, powdered espresso, vanilla extract and sugar. Stir in the cooled chocolate mixture. Set aside.

Sift together flour, baking powder and salt. Mix into the batter. Fold in remaining 3 cups chocolate chips and the walnuts. Pour into the greased pan. Bake about 30 minutes, or until a wooden pick just comes out clean. Do not overbake. Cool thoroughly and cut into squares.

NOTE: Halfway through baking, open the oven, lift and pan, and smack it on the rack. Turn the pan around and smack the other side. This stops the rising process and gives the brownies their wonderfully dense texture.

Makes 20.