Preheat oven to 325 F. Lightly butter and flour a large baking sheet.

Stir the eggs, instant coffee and vanilla in a small bowl until well blended; set aside. Mix the flour, baking powder and salt in a medium bowl; set aside.

Beat the butter and sugar in a large bowl with a mixer set on medium speed until light and fluffy. Beat in the egg mixture. Gradually add the flour mixture, beating well after each addition. Stir in chocolate chips.

Divide the dough into 2 equal portions. On a lightly floured surface, shape the dough into two logs, each 14 inches long, 1 inch wide and 1 inch thick. Place the logs 2 inches apart on the prepared baking sheet.

Bake for 25 minutes or until lightly browned. Set the baking sheet on a wire rack to cool for 10 minutes.

Remove the logs from the baking sheet and place on a cutting board. Using a serrated knife, cut each log diagonally into 3/4 inch slices. Place the slices upright and 1/2 inch apart on the baking sheet. Bake for 10 minutes or until slightly dry. Remove biscotti from baking sheet and place on wire rack until cool.

Melt white chocolate in microwave and pipe onto biscotti. (You can add 1 T. of shortening to white chocolate to ensure smooth chocolate.)