1 cup nuts (walnut, pecan or hazelnut; skin-on)
6 ounces semisweet chocolate morsels
½ cup unsalted butter, softened at room temperature
½ cup packed light brown sugar
½ cup sugar
2 large eggs
1 teaspoon vanilla extract
1 tablespoon instant espresso powder or finely ground coffee
½ cup high quality Dutch-processed cocoa powder, sifted
2½ cups unbleached flour
1 teaspoon baking powder
½ teaspoon salt
2 egg whites
½ cup sugar
½ teaspoon orange extract
Position oven racks in the middle and top of the oven and heat to 375 degrees.
Put the nuts in an even layer on a baking sheet and toast until they are well browned about 7 minutes. Let cool and then chop nuts to a size about ¼ inch or smaller.
With an electric mixer, beat the butter on medium until light and creamy. Beat in the sugars and eggs, one at a time. Add the vanilla, espresso and cocoa powder, scraping down the sides of the bowl as needed.
Add the flour, baking powder and salt, then the nuts and chocolate morsels, mixing just to combine. The dough will be stiff and a bit sticky. Let the dough rest 30 minutes before shaping.
Line two cookie sheets with parchment. Divide the dough into 3 pieces. Using a small amount of flour on the work surface, roll each piece into logs that are 12-14 inches long and 1½ inches wide. Transfer the logs to the baking sheets, 3 inches apart. Pat and smooth the tops and sides.
In a small bowl beat the egg whites with the orange extract until foamy. Brush the logs with some of the whites. Sprinkle with the sugar. Bake until set but not firm, about 20-25 minutes. Set the sheets on racks until the logs are cool enough to handle.
If you prefer a soft and chewy biscotti, you can stop here. If you prefer a double-baked cookie for dunking, cut the logs into ½-inch slices when they are cool. Place the slices topside up, space about ½ inch apart and return to oven for 7-10 minutes. Set the baking sheets on racks until cool. Sprinkle with powdered sugar, if desired. If stored in an airtight container, they will keep for two weeks. They can also be frozen.
Makes five dozen.