In a large mixing bowl, cream butter and 1 cup plus 2 tablespoons sugar until light and fluffy. Beat in remaining eggs and reserved egg yolk. Beat in extract.
Combine flour, baking powder and baking soda; gradually add to the creamed mixture.
Turn onto floured surface. Knead in cherries and almonds. Divide dough in half; spape each portion into a 12x3" rectangle. Transfer to a greased baking sheet.
Beat reserved egg white; brush over dough. Sprinkle with remaining sugar.
Bake at 350F for 28-30 minutes. Cool 10 minutes.
Transfer to a cutting board; with a serrated knife, cut each rectangle diagonally into 18 slices. Place cut side down on greased baking sheet. Bake for 20-25 minutes, turning once. Remove to wire racks to cool.
In a microwave safe bowl, melt chocolate chips and 1 tablespoon shortening; stir until smooth. Drizzle over both sides of biscotti. Place on waxed paper; let stand until set.
Melt white chocolate and remaining 2 teaspoons shortening; stir until smooth. Drizzle over both sides of biscotti. Place on waxed paper; set stand until set. Store in an airtight container.