In a large microwave-safe bowl, combine bittersweet chocolate and butter. Microwave on 50 percent power (medium) for 2 to 3 minutes or until melted, stirring twice.
Add eggs, brown sugar, coffee liqueur, vanilla, baking powder, and salt. Beat with a wooden spoon until combined. Beat in flour until combined. Stir in dark chocolate chunks, espresso coffee beans, and pecans. Cover and chill for 30 minutes.
Preheat oven to 350 degrees F. Lightly grease a large cookie sheet. Drop dough by rounded teaspoons 2 inches apart onto prepared cookie sheet.
Bake in the preheated oven for 8 to 10 minutes or until edges are firm and tops are dull and crackled. Cool on cookie sheet for 2 minutes. Transfer cookies to a wire rack; let cool. Makes about 48 cookies.
Layer cookies between waxed paper in an airtight container; cover. Store at room temperature for up to 3 days or freeze for up to 3 months.