1. In a microwave, melt 1 cup chocolate chips, unsweetened chocolate and butter for 30 seconds at a time. Stir until smooth. . Cool 10 minutes.
2. In a large bowl, beat sugar and eggs 2 minutes. Beat in chocolate mixture and vanilla.
3. In another bowl, whisk flour, cocoa, baking powder and salt; gradually beat into the chocolate mixture. Stir in remaining chocolate chips. Refrigerate, covered, until firm enough to handle, at least 1-2 hours.
4. Preheat oven to 350°. With lightly floured hands, shape dough into 1 inch balls and place onto a Silpat lined baking sheet. Bake until lightly puffed and set, 10-12 minutes. Cool on pans 3 minutes. Remove to wire racks to cool. Dust with confectioners’ sugar if desired.