Step 1Beat butter until creamy. Beat in sugar then egg whites, egg substitute, vanilla and hazelnut extracts. Stir in cherries, nuts and zest.
Step 2Combine flour, baking powder and salt. Stir into batter until blended.
Step 3Divide dough in half. Pat each half into a 12-inch log on a baking sheet sprayed with nonstick cooking spray. Flatten each log to 1 inch thick. Bake at 375 degrees until lightly browned, 25 to 30 minutes. Cool on rack, then slice logs diagonally into 1/2-inch slices. Reduce oven to 325 degrees and bake biscotti slices until lightly browned and crispy, 15 to 20 minutes.
Step 4Heat chocolate in double boiler set over, but not touching, simmering water until chocolate is melted. Dip one side of each biscotti into chocolate and put on wire rack to harden.