- 1
Preheat the oven to 350°F (180°C). Line a baking sheet with parchment paper. In a small bowl, whisk the egg white with 1 teaspoon water; set aside.
- 2
In a bowl, whisk together the flour, baking powder, and salt. In a large bowl, using an electric mixer on medium-high speed, beat the butter and granulated sugar until light and fluffy, about 2 minutes. Add the 2 eggs and almond and vanilla extracts and beat on low speed until the eggs are incorporated. Beating on low speed, slowly add the flour mixture and continue to beat until almost fully incorporated, scraping down the sides of the bowl as needed. Add the pistachios and apricots and cranberries and beat on low speed just until distributed.
- 3
Divide the dough in half. Shape each piece into a 91⁄2-by-11⁄2-inch (24-by-4-cm) square log and transfer the logs to the prepared baking sheet, spacing them 4 inches (10 cm) apart. Brush the logs with the egg white mixture and sprinkle with the sanding sugar.
- 4
Bake until the edges of the biscotti are light brown and the tops feel firm, 20 - 24 minutes. Remove the cookies and leave the oven on. Transfer the sheet to a wire rack and let cool slightly, about 20 minutes. Using a serrated knife, cut each log into 22 slices about 1⁄2 inch (12 mm) thick. Arrange the slices, cut side down, on the sheet and bake until the biscotti are golden brown and completely dry, 10 - 12 minutes. Using a metal spatula, transfer the biscotti to a wire rack and let cool completely.
- 5
Store the cookies in an airtight container, layered between sheets of parchment paper, in the refrigerator for up to 1 week.