Preheat oven to 350°.
Place first 6 ingredients in a large bowl, and beat with a mixer at medium speed until well blended.
Lightly spoon flour into dry measuring cups; level with a knife. Combine flour, instant coffee granules, cocoa, baking soda, ground cinnamon, salt, and ground nutmeg; gradually add to sugar mixture, beating until well blended. Stir in the cashews. Turn dough out onto a lightly floured surface; knead lightly 7 times. Divide dough in half. Shape each portion into a 12-inch-long roll. Place rolls on a baking sheet coated with cooking spray; pat to 3/4-inch thickness. Sprinkle rolls evenly with 1 tablespoon granulated sugar.
Bake at 350° for 22 minutes. Remove rolls from baking sheet; cool 10 minutes on a wire rack. Cut each roll diagonally into 21 (1/2-inch) slices. Carefully stand slices upright on baking sheet. Reduce oven temperature to 325°; bake 20 minutes (the cookies will be slightly soft in center but will harden as they cool). Remove from baking sheet, and cool completely on wire rack.
Place chocolate in a small heavy-duty zip-top plastic bag; microwave at high 1 minute or until the chocolate is soft. Knead bag until smooth. Snip a tiny hole in corner of bag; drizzle chocolate over biscotti.