- In a large bowl, beat butter with an electric mixer on medium to high for 30 seconds. Add sugar, baking powder, and salt. Beat until combined, scraping sides of bowl occasionally. Beat in egg and vanilla until combined. Beat in as much of the flour as you can with the mixer. Using a wooden spoon, stir in any remaining flour, Makes about 2-1/2 cups of dough.
- Divide dough into thirds. Knead coffee powder into one portion of the dough. Stir chocolate into one portion of the dough (knead if necessary). Leave remaining portion plain. Divide each dough portion in half. Cover and chill about 1 hour or until easy to handle.
- On waxed paper, roll one portion of the chocolate dough into an 8x6-inch rectangle (keep remaining dough chilled); place waxed paper with dough rectangle on a cookie sheet, dough side up. On another sheet of waxed paper, roll one portion of the plain dough into an 8x6-inch rectangle. Invert plain dough onto chocolate dough; peel off waxed paper. On same piece of waxed paper, roll one portion of the coffee dough into an 8x6-inch rectangle. Invert coffee dough onto plain dough; peel off waxed paper. Repeat with remaining chocolate, plain, and coffee doughs to form a six-layer stack. Press together lightly. Wrap stack in plastic wrap. Chill for 1 hour.
- Preheat oven to 375 degrees F. Trim edges of the dough stack. Cut dough stack in half lengthwise, forming two rectangles. Cut each rectangle crosswise into 1/4-inch-thick slices. Arrange slices, cut sides down, 2 inches apart on an ungreased cookie sheet. Bake about 8 minutes or until edges are lightly browned. Transfer cookies to a wire rack; cool. Makes about 48 cookies.
From the Test Kitchen
Prepare, bake, and cool cookies as directed. Layer cookies between waxed paper in an airtight container. Cover; seal. Store at room temperature for up to 3 days or freeze for up to 1 month. Used chilled dough directly form the refrigerator. For frozen dough, thaw overnight in the refrigerator and then use.