Directions:

1. Preheat oven to 350°F. Line 2 baking sheets with parchment paper.
2. Meanwhile, coarsely chop 14-ounces of bittersweet chocolate and place in a stainless steel bowl with unsweetened chocolate and espresso powder. Place bowl over a saucepan of simmering water (do not allow bottom of bowl to touch water). Stir chocolate frequently with a whisk until completely melted. Remove from heat. You can also melt chocolate in the microwave in a microwave-safe bowl on medium-high power at 30-second intervals, stirring frequently until chocolate is melted. Allow to cool. Reserve.
3. In a small bowl, combine flour, baking powder, and salt. Reserve. Coarsely chop remaining 12-ounces of bittersweet chocolate. Reserve.
4. Using an electric mixer, whip butter, vanilla, and sugar until smooth – approximately 3 minutes. Add in the eggs one at a time until just combined.
5. With the mixer on low, slowly add the cooled chocolate to the batter. Be careful not to over mix. Next, add the flour mixture and mix until just combined – approximately 1 minute. Fold in the remaining 12-ounces of bittersweet chocolate, semi-sweet chocolate, and nuts by hand.
6. Place golf ball-sized scoops of batter an inch apart on the baking sheets. Bake until the edges are set and the top is slightly cracked but still moist in the center – approximately 15-17 minutes.
7. Cool for 1 minute then remove from baking sheets. Serve warm or cooled to room temperature.