How to Make It
Preheat oven to 300°.
Place liqueur in a small bowl. Microwave at HIGH 10 seconds. Stir in cocoa and espresso until smooth. Add oil, egg whites, and egg, stirring with a whisk until blended.
Lightly spoon flours into dry measuring cups; level with a knife. Place flours, sugars, 2 tablespoons hazelnuts, baking soda, and salt in a food processor; process until nuts are ground. Add ground coffee; pulse 2 times or until blended. With processor on, slowly add liqueur mixture through food chute; process until dough forms a ball. Add remaining 6 tablespoons hazelnuts; pulse 5 times or until blended (dough will be sticky). Turn dough out onto a floured surface, and knead lightly 4 or 5 times. Divide into 3 equal portions, shaping each portion into a 10-inch-long roll. Place rolls 3 inches apart on a large baking sheet coated with cooking spray. Bake at 300° for 28 minutes. Remove rolls from pan; cool 10 minutes on a wire rack.
Cut each roll diagonally into 20 (1/2-inch) slices. Place slices, cut sides down, on baking sheets. Bake at 300° for 20 minutes. Turn cookies over; bake an additional 10 minutes (cookies will be soft in center but will harden as they cool). Remove cookies from pans; cool completely on wire racks.