4 oz. semisweet chocolate, coarsely chopped
1 cup firmly packed light brown sugar
1 3/4 cups unbleached all-purpose flour
1/3 cup unsweetened cocoa, preferably Dutch process
1 1/2 Tbs. instant espresso powder
1 tsp. baking soda
1/4 tsp. salt
3 eggs
1 1/4 tsp. vanilla extract
1/2 tsp. almond extract
1 cup hazelnuts, toasted and coarsely chopped

For the chocolate coating:
8 oz. semisweet or bittersweet chocolate, chopped
2 tsp. vegetable shortening

Preheat an oven to 300°F. Line a large baking sheet with parchment paper or waxed paper.

In a food processor fitted with the metal blade, combine the chocolate and brown sugar and process until the chocolate is very fine; set aside. Alternatively, use a blender, processing 1 oz. chocolate and 1/4 cup sugar at a time.

Sift together the flour, cocoa, espresso powder, baking soda and salt into a bowl; set aside. Combine the eggs, vanilla extract and almond extract in a large bowl. Using an electric mixer set on medium speed, beat to blend. On low speed, mix in the sugar and flour mixtures until a stiff dough forms, adding the hazelnuts when the dough is about half mixed.

On a floured surface, divide the dough in half. Form each half into a log 12 inches long. Transfer the logs to the prepared baking sheet, spacing them well apart, and pat to even the shapes. Bake until almost firm to the touch, about 50 minutes (logs will spread during baking). Remove from the oven and let cool for 10 minutes. Leave the oven set at 300°F.

Using a spatula, carefully transfer the logs to a work surface. Using a serrated knife, cut logs on the diagonal into slices 1/2 to 3/4 inch thick. Arrange the slices, cut side down, on the baking sheet. Bake 25 minutes. Turn the slices over and bake until crisp and dry, about 25 minutes more. Turn off the oven and let cool completely in the oven with the door slightly ajar.

Meanwhile make the chocolate coating: Combine the chocolate and shortening in the top pan of a double boiler. Melt over but not touching simmering water just until smooth, stirring occasionally. Remove from the heat. Alternatively, melt the chocolate and shortening in a heatproof bowl placed over but not touching simmering water.

Dip one side of the cooled cookies in the hot chocolate coating and set, chocolate side up, on a baking sheet. Refrigerate until set. Store in an airtight container in the refrigerator for up to 2 weeks. Makes about 30 biscotti.