1In medium microwavable bowl, microwave chocolate and butter uncovered on High 1 minute to 1 minute 30 seconds, stirring every 30 seconds, until melted and smooth. Cool 10 minutes.
2Meanwhile, in small bowl, stir together flour, baking powder and salt; set aside. In large bowl, beat brown sugar, eggs, espresso powder and vanilla with electric mixer on medium speed 3 minutes. Add cooled chocolate mixture; beat on low speed until blended. Add flour mixture; beat until soft dough forms. Stir in chocolate chips. Refrigerate dough 30 minutes or until firm enough to handle.
3Heat oven to 350°F. Shape dough into 2-inch balls. Onto ungreased cookie sheets, place balls 2 inches apart. Bake 10 to 12 minutes or until tops are cracked and dry (cookies will still be soft). Cool 3 minutes; remove from cookie sheets to cooling racks. Cool completely before storing in airtight container.