Preheat the oven to 350 degrees. Grease two (81/2 × 41/2 inch) loaf pans. Line the pans with parchment paper, then spray with cooking spray for easy removal, and set aside.

Pour the boiling water into a 2-cup glass measuring cup, then add the bitter-sweet chocolate, cocoa powder, and coffee granules, and stir until the chocolate melts. Set the chocolate mixture aside to cool for at least 15 minutes.

Sift together the 2 cups flour, the baking powder, and salt in a medium bowl, set aside.

In small bowl combine the walnuts, chocolate chips, and the 2 tablespoons flour and set aside.

In the bowl of an electric mixer fitted with the paddle attachment or using an electric mixer, beat the butter, granulated sugar, and brown sugar together on medium speed for 2 minutes.

Turn the mixer on low speed and add the eggs, one at a time, then the vanilla extract. Be sure to scrape the sides and the bottom of the bowl with a rubber spatula.

Alternately,  in thirds, add the flour mixture and the chocolate mixture, beginning and ending with the flour.

Fold in the nut and chocolate mixture with a rubber spatula.

Divide the cake batter equally between the prepared parchment-lined loaf pan, then smooth the tops.

Bake loaf cake for 45-55 minutes, until a toothpick or a cake tester inserted in the middle of the loaf comes out clean. Check in a few areas just in case you hit a melted chocolate chip.

Cool in the pans for 30 minutes, then turn out on wire rack, rounded side up. Let the cake cool to room temperature.