Place chopped chocolate and butter in microwave-safe bowl. Microwave until melted, stirring every 30 seconds. Set aside to cool slightly.
Beat brown sugar and chocolate on high speed of an electric mixer until light and fluffy. Add eggs, one at a time, beating well after each addition. Set aside.
in a separate bowl, combine flour, espresso powder, baking powder, and salt. Turn mixer on low speed and gradually add flour mixture to chocolate mixture. Beat until smooth. Stir in chocolate chips. Wrap dough in plastic wrap. Refrigerate about 4 hours.
Preheat oven to 350. Line baking sheets with parchment paper or silicone liners.
Roll dough into 1-inch balls. Place two inches apart on baking sheets. Bake 9-10 minutes, or until browned around the edges. Cool cookies on wire racks. Sprinkle with confectioners’ sugar.
Makes about 3 dozen cookies.