1. Preheat oven to 350 degrees F. Grease large baking sheet.
2. Cook hazelnuts in large skillet over medium-low heat until lightly toasted, 3 to 4 minutes. Rub nuts in clean dish towel to remove skins. Coarsely chop.
3. Combine flour, sugar, espresso, cinnamon, baking powder and salt in a bowl. With pastry blender, cut in butter to form coarse crumbs. Stir in nuts and eggs. Divide mixture in half.
4. On floured surface, with floured hands, roll each half into 12-inch-long log. Flatten to 2-1/2-inch width. Place logs, about 4 inches apart, on prepared baking sheet.
5. Bake in preheated 350 degree F oven for 30 minutes or until cookies are slightly firm to the touch. With 2 spatulas, transfer logs to wire rack to cool for 20 minutes.
6. With a serrated knife, cut the logs diagonally into 3/4-inch-thick slices. Return biscotti to cookie sheet. Bake 10 to 15 minutes until crisp and firm to touch. Transfer to rack to cool.
7. Melt chocolate, stirring occasionally, in small saucepan over low heat. Remove from heat. Stir in shortening until well blended. Dip one flat side of biscotti in chocolate. Dip one end and half of other flat side into chocolate. Transfer biscotti to waxed-paper-lined baking sheet. Repeat with remaining biscotti. Refrigerate biscotti until chocolate hardens completely, 30 minutes.
8. Store unfrosted biscotti in airtight container for up to 2 weeks. Frost up to 2 days before using or giving.