- Sift together flour, cocoa, baking powder and salt. Melt chocolate over simmering water or gently in the microwave, stirring occasionally, until smooth. Set aside.
- Beat eggs with a fork to break them up. Add vanilla and sprinkle with coffee powder. Set aside.
- Beat butter 30 seconds or so until smooth and creamy. Add sugars, beating until well combined. Add eggs and beat until well combined. Add chocolate in a steady stream (or by large spoonsful), removing remains with a scraper. Scrape the sides of the bowl and beat to combine all. Add flour and mix on low speed just until combined—less than a minute. Cover the bowl with plastic wrap and let it stand 30 minutes to set.
- Heat oven to 350°, arranging racks in the upper and lower middle of the oven. Line 2 cookie sheets with parchment paper. Scoop dough into heaping tablespoons and place 1½ inches apart on parchment.
- Bake cookies until the edges are set and centers are soft, about 10 minutes, switching their positions front to back and bottom and top at about 5 minutes. Cool on baking sheets 10 minutes, then slide parchment onto cooling racks to cool completely. Use a metal spatula to remove cookies.
Makes about 32 cookies