Sift together and set aside:
2 cups flour
½ cup Dutch-processed cocoa powder
2 tsp. baking powder
1 tsp. salt
Melt in the microwave:
16 oz. semisweet chocolate, chopped
In another bowl beat lightly with a fork:
4 large eggs
2 tsp. vanilla
Sprinkle over eggs to dissolve and set aside:
2 tsp. instant coffee or espresso powder
In large mixing bowl beat at medium speed until smooth and creamy (about 5 seconds with standing mixer, 15 seconds with hand mixer):
10 T. (1 ¼ sticks) unsalted butter
Add and beat until combined (45 seconds with standing mixer, 1 ½ minutes for hand mixer); mixture will granular:
1 ½ cups light brown sugar, packed
½ cup sugar
Reduce speed to low and gradually beat in egg mixture. (45 seconds with standing, 1 ½ with hand mixer)
Add chocolate to butter mixture in a steady stream and beat until combined. Scrape bottom and sides of bowl with rubber spatula. With mixer at low speed, add flour mixture and mix until combined. Do not overbeat. Cover with plastic wrap and let stand at room temperature until consistency is scoopable and fudgelike, about 30 minutes.
Meanwhile, adjust oven racks to upper-middle and lower-middle positions and heat oven to 350°. Line 2 cookie sheets with parchment paper. Leaving about
1 ½ inch between each ball, scoop dough onto parchment-lined cookie sheets. Balls should be the size of a golf ball. (If using a cookie scoop, use 1 ¾” diameter ice cream scoop.
Bake cookies until edges have just begun to set but centers are still 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 for 10 minutes, slide parchment with cookies onto wire rack and cool to room temperature.