Preparation Preheat oven to 350°F. Line 3 baking sheets with waxed paper. Lightly flour waxed paper. Sift flour and baking powder into medium bowl. Beat sugar and butter in large bowl until blended. Add eggs, 1 at a time, beating until fluffy. Mix in nuts and candied orange peel. Add flour mixture and liqueur; beat until well blended. Spoon dough out onto 1 prepared baking sheet, pressing to form 12-inch-long rectangle, about 5 inches wide (dough will be very soft). Place in freezer until firm, about 30 minutes. Cut chilled dough lengthwise into 3 strips. Shape each strip on lightly floured surface into 12-inch-long, 1 1/2-inch-wide and 1-inch-high log. Transfer logs to remaining 2 prepared sheets, 1 log on 1 sheet and 2 logs on second sheet, spacing 2 inches apart. Brush logs with egg yolk. Bake until golden and firm to touch (dough will spread), about 30 minutes. Cool completely on baking sheets. Reduce oven temperature to 325°F. Using serrated knife, cut logs into 3/4-inch-wide diagonal slices. Stand biscotti slices upright on 2 heavy large baking sheets. Bake until biscotti are pale golden, about 25 minutes. Transfer to racks and cool. (Can be prepared 1 week ahead. Store in airtight container.)
Preparation Preheat oven to 350°F. Line 3 baking sheets with waxed paper. Lightly flour waxed paper. Sift flour and baking powder into medium bowl. Beat sugar and butter in large bowl until blended. Add eggs, 1 at a time, beating until fluffy. Mix in nuts and candied orange peel. Add flour mixture and liqueur; beat until well blended. Spoon dough out onto 1 prepared baking sheet, pressing to form 12-inch-long rectangle, about 5 inches wide (dough will be very soft). Place in freezer until firm, about 30 minutes. Cut chilled dough lengthwise into 3 strips. Shape each strip on lightly floured surface into 12-inch-long, 1 1/2-inch-wide and 1-inch-high log. Transfer logs to remaining 2 prepared sheets, 1 log on 1 sheet and 2 logs on second sheet, spacing 2 inches apart. Brush logs with egg yolk. Bake until golden and firm to touch (dough will spread), about 30 minutes. Cool completely on baking sheets. Reduce oven temperature to 325°F. Using serrated knife, cut logs into 3/4-inch-wide diagonal slices. Stand biscotti slices upright on 2 heavy large baking sheets. Bake until biscotti are pale golden, about 25 minutes. Transfer to racks and cool. (Can be prepared 1 week ahead. Store in airtight container.)