Makes 26 cookies
3 ounces unsweetened chocolate, chopped
1 1⁄2 cups bittersweet chocolate chips
7 tbls. unsalted butter, cut into pieces
2 tsp. instant coffee
2 tsp. vanilla extract
3 large eggs, at room temperature
1 c. sugar
1⁄2 c. all-purpose flour
1⁄2 tsp. baking powder
1⁄2 tsp. table salt
1 1⁄2 c. semisweet chocolate chips
1. Melt unsweetened chocolate, bittersweet chips, and butter in heatproof bowl set over saucepan of simmering water, stirring frequently, until completely smooth and glossy. Remove bowl from pan and set aside to cool slightly.
2. Stir coffee powder and vanilla extract together in small bowl until dissolved. Beat eggs and sugar in large bowl with electric mixer at medium-high speed until very thick and pale, about 4 minutes. Add vanilla-coffee mixture and beat until incorporated, 20 seconds. Reduce speed to low, add chocolate mixture, and mix until thoroughly combined, about 30 seconds.
3. Whisk flour, baking powder, and salt together in medium bowl. Using large rubber spatula, fold flour mixture and semisweet chips into batter. Cover blow with plastic wrap and let stand at room temperature for 20 to 30 minutes until batter firms up (it will more closely resemble thick brownie batter than cookie dough).
4. Meanwhile, two oven racks to upper and lower middle positions and heat oven to 350 degrees. Line two large baking sheets with parchment paper. Using 1 heaping tablespoon batter per cookie, place cookies 2 inches apart on parchment paper on baking sheets. Bake until cookies are shiny and cracked on top, 11 to 14 minutes, rotating sheets top to bottom and front to back halfway through baking time. Transfer baking sheets to racks and cool cookies completely, on baking sheets, before serving.