Mosaic Biscotti

3.5 cups unbleached all purpose flour
1 teaspoon baking powder
1 teaspoon kosher salt
4 large eggs
2 large egg yolks, plus 1 egg white for glaze
2 cups sugar, plus 1.5 tablespoons for glaze
2 teaspoons pure vanilla extract
12 ounces semisweet or bittersweet chocolate, coarsely chopped (I used Ghiaredelli chips)
2 cups skinned or unskinned hazelnuts
2 cups whole, unsalted pistachios, coarsely chopped (I left mine whole)
(When I made them, I cut back on the chocolate a little bit and added about a cup of dried cranberries)

In a medium bowl, whisk together flour, baking powder and salt and set aside.

Beat together the eggs, egg yolks and 2 cups of the sugar on medium speed until pale and thick, about 2 minutes.  Beat in the vanilla extract, followed by the dry ingredients and then the chocolate and nuts, until the dough is thoroughly mixed. 

Preheat the oven to 325 degrees.  Lightly grease two large baking sheets with nonstick cooking spray or butter or line with parchment (no clean up, if you do this - my preferred method!)

Using floured hands, divide the dough into 5 equal portions*.  On a lightly floured surface, shape each portion of the dough into a log about 1.5 inches in diameter and 10 inches long.  Place 2 of the logs on one of the baking sheets, 3 inches apart, and 3 of the logs on the second baking sheet, also 3 inches apart.  In a small bowl, beat the egg with a fork until frothy.  With a pastry brush, glaze each log with the beaten egg white and sprinkle with the remaining sugar.

Bake the logs until they are lightly golden brown, firm to the touch, and just beginning to crack slightly, 20 to 25 minutes.  Rotate the sheets 180 degrees halfway through the baking time to ensure even browning.  Allow the logs to cool on the baking sheets on a wire rack until they are cool to the touch, about 40 minutes.  Reduce the oven temperature to 200 degrees.

With a sharp, serrated knife, slice the biscotti slightly on the bias into 1/4 inch wide slices.  Lay the slices on the baking sheets in a single layer.  Return them to the oven and cook for 20 minutes more, or until they are toasted, dry and crisp.  Cool the biscotti completely on the sheets and then store them in an airtight container kept in a cool, dry place for up to 2 weeks.

*You may make the biscotti any size you like.  For larger biscotti, divide the dough into only 4 pieces.  Make the logs a little wider and you will have longer biscotti.  You can also cut the biscotti into 1/2 inch slices if you like.