2-1/4 cups unbleached all-purpose flour
1 tsp baking powder
1/2 tsp baking soda
1/4 tsp salt
1/4 tsp ground white pepper
1/2 tsp cloves
1/2 tsp cinnamon
1/4 tsp ginger
1 cup sugar
2 large eggs plus 2 yolks
1/2 tsp vanilla extract
1. Sift first 8 ingredients together in a small bowl.
2. Whisk sugar and eggs to a light lemon color; stir in vanilla extract. Sift dry ingredients over egg mixture, then fold in until dough is just combined.
3. Adjust oven rack to middle position and heat oven to 350 degrees F. Halve dough and turn each portion onto an oiled cookie sheet covered with parchment. Using floured hands, quickly stretch and shape dough into two rough 13" by 2" logs. Flatten the logs a bit until about 3/4-inch high. Position the logs about 3" apart on the cookie sheet. Bake until loaves are golden and just beginning to crack on top, about 35 minutes. Turn pan around once during baking.
4. Cool the loaves for 10 minutes; lower oven temperature to 325 degrees F. Cut each loaf diagonally into 3/8-inch slices with a serrated knife. I used my bread knife. Lay the slices about 1/2-inch apart on the cookie sheet, cut side up, and return them to the oven. Bake, turning over each cookie halfway through the second baking, until crisp and golden brown on both sides, about 15 mins. Transfer biscotti to wire rack and cool completely.