To melt the chocolate in a microwave, heat at 50% power for 2 minutes, stir, then continue heating at 50% power for 1 more minute. If not completely melted, heat an additional 30 to 45 seconds at 50% power. Semisweet chocolate chips may be added for a bigger chocolate punch; if used, they will slightly increase the yield on the cookies. We recommend using spring-loaded ice cream scoop to scoop the dough. Resist the urge to bake the cookies longer than indicated; they may appear under baked at first but will firm up as they cool.
MAKES ABOUT 3 1/2 DOZEN COOKIES
2 cups all-purpose flour
1/2 cup Dutch-processed cocoa powder
2 teaspoons baking powder
1 tsp. salt
16 ounces semisweet chocolate, chopped
4 large eggs
2 tsp. vanilla extract
2 tsp. instant coffee or espresso powder
10 Tbs. (1 1/4 stick) unsalted butter, softened but still firm
1 1/2 cups packed brown sugar
1/2 cup granulated sugar
Sift together flour, cocoa, baking powder, and salt in medium bowl; set aside. Melt chocolate in medium heatproof bowl set over pan of almost simmering water, stirring once or twice, until smooth; remove from heat. Beat eggs and vanilla lightly with fork, sprinkle coffee powder over to dissolve, and set aside.
In bowl of standing mixer fitted with paddle attachment (or with hand mixer), beat butter at medium speed until smooth and creamy, about 5 seconds. Beat in sugars until combined, about 45 seconds; mixture will look granular. Reduce speed to low and gradually beat in egg mixture until incorporated, about 45 seconds. Add chocolate in steady stream and beat until combined, about 40 seconds. Scrape bottom and sides of bowl with rubber spatula. With mixer a low speed, add flour mixture and mix until combined, about 40 seconds. Do not over-beat. (Stir in chocolate chips with wooden spoon). Cover with plastic wrap and let stand at room temperature until consistency is scoopable and fudge-like, about 30 minutes.
Meanwhile, adjust oven racks to upper- and lower-middle position and heat oven to 350°. Line cookies sheets with parchment paper. Leaving about 1 1/2 inches between each ball, scoop dough onto parchment-lined cookie sheets with 1 3/4-inch diameter ice cream scoop.
Bake cookies until edges have just begun to set but centers are still very soft, about 10 minutes, turning cookie sheets from front to back and switching from top to bottom racks halfway through baking.
Cool cookies on sheets about 10 minutes, slide parchment with cookies onto wire rack and cool to room temperature; remove with wide spatula.