Chocolate Hazelnut Spiced Cookies

From Gourmet [1]

For cookies:
1 1/2 cups hazelnuts (9 ounces), toasted , loose skins rubbed off in a kitchen towel while still warm, and nuts cooled completely
3/4 cup sugar
1/2 cup all-purpose flour
1/2 cup unsweetened cocoa powder (not Dutch-process)
1 teaspoon baking soda
3/4 teaspoon salt
1/2 teaspoon ground cinnamon
1/8 teaspoon ground cloves
3 tablespoons cold unsalted butter, cut into 1/2-inch cubes
1 tablespoon grated orange zest
3 tablespoons fresh orange juice
1 tablespoon hazelnut-flavored liqueur (preferably Frangelico)
For icing:
1/2 cup confectioners sugar
1/2 cup unsweetened cocoa powder (not Dutch-process)
3 tablespoons water
1 tablespoon hazelnut-flavored liqueur

Make cookies: Preheat oven to 325°F with rack in middle. Butter a large baking sheet.
Pulse hazelnuts, sugar, flour, cocoa powder, baking soda, salt, cinnamon, and cloves in a food processor until nuts are finely chopped, then add butter and zest and pulse until mixture resembles coarse meal with some small (roughly pea-size) butter lumps.
Add juice and liqueur and pulse until dough comes together into a ball but is still crumbly. Form level tablespoons of dough into balls and flatten to about 1 1/2 inches in diameter, arranging 1 inch apart on baking sheet.
Bake cookies until puffed and slightly cracked, about 15 minutes. Transfer to a rack to cool completely.
Make icing while cookies cool: whisk together all icing ingredients until smooth.
Dip tops of cooled cookies into icing and transfer to a wax-paper-lined baking sheet. Let stand until icing is set, about 1 hour.

Makes 2 1/2 dozen cookies.

Make ahead: Cookies keep, layered between sheets of parchment paper, in an airtight container at room temperature 4 days.