In a large mixing bowl, stir together flour, hazelnuts, chocolate pieces, cocoa powder, espresso powder, baking powder, baking soda, and salt.
In a very large mixing bowl, beat butter for 30 seconds to soften. Gradually add sugar. Add eggs, one at a time, beating after each. Stir in the dry ingredients.
Divide dough in half. Shape each portion into a 12x2x1-inch log. Place 4 inches apart on ungreased cookie sheet.
Bake in a 375 degree F oven for 25 to 30 minutes or until lightly browned and edges are firm. Cool on a cookie sheet for 1 hour.
Cut each log diagonally into 1/2-inch slices. Lay slices, cut sides down, on the ungreased cookie sheet.
Bake in a 325 degree F oven for 5 minutes; turn pieces over. Bake for 5 to 10 minutes more or until dry and crisp. Remove; cool.
In a small, heavy saucepan, melt white baking bar and shortening over low heat, stirring occasionally. Drizzle over slices. Makes about 40 biscotti.