准备

混合面团。

• 将烤箱架放在烤箱的中间和顶部，然后将烤箱加热至350°F。在烤盘上烤榛子，直到它们变褐色，大约10分钟。冷静。您不需要剥皮 - 皮肤的味道很棒 - 但如果坚果大于1/2英寸，请大致切碎。将巧克力切成1英寸长，宽1/8英寸的巧克力。
• With an electric mixer fitted with the paddle attachment, beat the butter on medium-high speed until light and creamy. Add the eggs one at a time. Add the brown and white sugars, vanilla extract, almond extract, espresso powder, and cocoa powder, scraping down the sides of the bowl as needed. Add the candied orange peel, flour, baking powder, and salt. Add the hazelnuts and chocolate slivers, mixing just to combine. The dough will be stiff and a bit sticky. Let the dough rest for 15 to 30 minutes before shaping.

Shape and bake the dough.

• 两条大烤盘和羊皮纸。将面团分为六个相等的块。在工作表面上使用尽可能少的面粉，将每件块滚动成长12到14英寸，宽1-1/4英寸的原木，并在旅途中锻炼空气口袋。（如果您要努力，请用保鲜膜包裹原木，然后将其冷藏过夜）。将原木转移到衬有衬里的烤盘上，将面团相距约3英寸，拍拍侧面以使其平滑，直截了当。在一个小碗中，用橙色提取物打成蛋清，直到泡沫。用一些白色刷原木的顶部和侧面。撒上1/4杯糖。烘烤，直到牢固地牢牢地在中心，大约35分钟，旋转床单以确保烘烤。将床单放在架子上，直到原木凉爽到足以处理，因此切割时面团不会压缩，大约30分钟。

第二次烘烤。

• Reduce the oven to 300°F and line the baking sheets with fresh parchment, if needed. With a serrated knife, saw the strips into 1/2-inch-thick slices, cutting crosswise. Lay the slices flat on the baking sheets. Brush the tops with the beaten egg white and sprinkle with another 1/4 cup of the sugar. Bake about 15 minutes, rotating the baking sheets as needed. Turn the biscotti over. Brush again with the egg white and sprinkle with the remaining 1/4 cup sugar. Bake another 10 to 15 minutes, watching carefully to make sure the chocolate doesn’t burn. The centers will feel somewhat soft even when fully baked; they’ll harden as the cookies cool. Set the baking sheets on racks, letting the cookies cool and crisp completely on the sheets. If stored airtight, the biscotti will keep for about two weeks.

For a more intense chocolate flavor, replace the chocolate and cocoa with a 9.2-oz. bar of Scharffen Berger 62% semisweet chocolate along with 3/4 cup each Scharffen Berger nibs and cocoa.