Preheat oven to 350°.
To prepare cookies, lightly spoon flour into dry measuring cups; level with a knife. Combine flour and next 6 ingredients (through cloves) in a medium bowl, stirring well with a whisk.
Place brown sugar and 1/4 cup butter in a large bowl; beat with a mixer at high speed until light and fluffy (about 4 minutes). Add 2 tablespoons syrup and egg; beat until well blended. Beating at low speed, gradually add flour mixture; beat just until combined.
Spoon batter evenly into 30 mounds (about 1 tablespoon) 2 inches apart on baking sheets. Bake at 350° for 14 minutes or until lightly browned. Cool on pans 5 minutes. Remove from pans; cool completely on wire racks.
To prepare frosting, combine powdered sugar, 2 tablespoons syrup, milk, and 2 teaspoons butter, stirring with a whisk until smooth. Spread frosting evenly over cooled cookies. Working quickly, sprinkle cookies with nuts.