Melt together the butter, 1 lb of chocolate chips, and the unsweetened chocolate in a medium bowl over simmering water. (I have an extra low setting on my stove, so I used that instead and watched it like a hawk!)
Allow to cool slightly
In a large bowl, whisk the eggs together with the coffee granules, 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 cup of the flour, the baking powder and the salt
Add the cooled chocolate mixture to the flour mixture
Toss the walnuts and 12 ounces of chocolate chips in a medium bowl with 1/4 C flour
Add to batter
Pour onto the baking sheet and spread to the edges
Bake for 20 minutes, then rap the baking sheet against the oven shelf to force the air to escape between the pan and the brownie dough
Bake for 15 minutes more or until a toothpick inserted in the middle comes out clean