How to Make It
Preheat the oven to 325°. In a bowl, sift together the flour, cocoa, baking powder, baking soda and salt. In a large bowl, using an electric mixer, cream the butter with the sugar. Beat in the eggs, 1 at a time. At low speed, gradually beat in the flour mixture. Fold in the chocolate chips and chocolate-covered espresso beans.
Divide the dough in half and form each half into a 2-inch-wide log. Transfer the logs to a large baking sheet and brush with the egg white. Bake for 30 minutes, then let cool on the baking sheet for 10 minutes.
Increase the oven temperature to 350°. Using 2 large metal spatulas, transfer the logs to a work surface. Cut each log crosswise into 1/2-inch slices. Arrange the slices on 2 large baking sheets, cut sides down, and bake for 15 minutes longer, until slightly dry. Let cool on the baking sheets.
Use a serrated knife to cut the biscotti log before re-baking it in Step 3. A serrated knife will make cleaner slices.