From the post: “Those” Biscotti.

Chocolate, Hazelnut and Ginger Biscotti (Bon Appetit, December 1999)
Makes about 48 biscotti.

1 2/3 cups all purpose flour
1 cup sugar
1/3 cup unsweetened cocoa powder
1 teaspoon baking soda
1/2 teaspoon salt
3 large eggs, plus one for brushing an egg wash
2 teaspoons vanilla extract
1 1/4 cups semi-sweet chocolate chips (8 oz.)
2/3 cup hazelnuts, toasted, husked and coarsely chopped
1/3 cup finely chopped crystallized ginger
6 oz. good quality milk chocolate such as Lindt, coarsely chopped
(The original recipe called for white chocolate, which looks prettier, but I prefer the taste of milk chocolate on these.)

Preheat oven to 350°F. Line a large baking sheet with parchment paper or use a silpat. Sift the first 5 ingredients into medium bowl. Add 3 eggs and vanilla; beat until blended. Stir in chocolate chips, nuts and crystallized ginger (dough will be firm). Turn dough out onto floured surface. Gather into ball. Divide dough in half. Roll each half into 12-inch-long log. Transfer logs to the prepared baking sheet, spacing 3 inches apart. Flatten each to 2 1/2-inch-wide log. Whisk remaining egg in small bowl to blend. Brush logs with some of beaten egg.

Bake logs until golden and firm to touch, about 35 minutes. Cool logs on baking sheet 15 minutes. Reduce oven temperature to 325°F.

Transfer logs to cutting board. Using a serrated knife, cut logs crosswise into scant 1/2-inch-wide slices. (This width is important in order to make a crisp cookie) Place slices, cut side down, on large baking sheets. Bake until firm, about 15 minutes. Transfer biscotti to racks and cool completely.

Stir the milk (or white) chocolate in top of double boiler set over barely simmering water until melted and smooth. Remove from over water. Place biscotti on rack set over baking sheet. Using a spoon, drizzle melted chocolate decoratively in zigzag pattern over biscotti. Let stand until chocolate is firm. (Can be prepared ahead. Store biscotti in airtight container at room temperature up to 2 weeks or freeze up to 1 month.)