Marbled Biscotti

3/4 cup semisweet chocolate chips
1/3 cup butter
3/4 cup granulated sugar
2 teaspoons baking powder
Pinch of salt
2 eggs
1/2 teaspoon pure vanilla extract
2 cups all-purpose flour
1/2 cup hazelnuts, coarsely chopped
1 1/2 teaspoons orange zest

Preheat oven to 350 degrees F. Lightly grease 2 baking sheets.

Melt chocolate chips in a double boiler over hot, but not boiling, water. Stir the chocolate occasionally until it is smooth. Remove from heat and cool.

In a large mixing bowl, beat butter on medium speed until it is creamy - approximately 1 minute. Add sugar, baking powder and salt; beat until blended. Beat in eggs and vanilla extract until combined. Stir in the flour with a wooden spoon. Divide dough in half and transfer one half to another bowl. Stir the melted chocolate and 1/4 cup of the hazelnuts into one half of the dough. Stir the orange zest and remaining nuts into the other half.

Divide each half into 4 equal parts. Using lightly floured hands, shape each portion into 1 1/4 x 10-inch ropes. Place a rope of each color side by side on one of the prepared baking sheets. Twist the ropes around each other several times. Flatten slightly to make a 2-inch wide log. Repeat with the other ropes, placing the logs about 4 inches apart on the baking sheets. Bake for 25 minutes, or until logs are firm to the touch. Cool on the baking sheets for 15 minutes, or until cool enough to handle. Lower the oven temperature to 300 degrees F.

Transfer one log to a cutting board and, with a serrated knife, cut log into twelve 1-inch wide cookies. Repeat with the remaining three logs. Remove one oven rack and place the 48 cookies directly on it. Return the rack to the uppermost position in the oven and crisp for 20 to 25 minutes. To test for doneness, remove one cookie; let it cool, then check it for crispness.