Preheat oven to 350°.
Beat the first 3 ingredients at medium speed of a mixer 4 minutes or until well-blended. Add egg, and beat well. Lightly spoon flour into a dry measuring cup; level with a knife. Combine flour, baking powder, and salt; gradually add to sugar mixture, beating until well-blended. Stir in chocolate-covered raisins.
Turn dough out onto a lightly floured surface, and knead lightly 7 times. Shape dough into a 12-inch-long roll. Place roll on a baking sheet coated with cooking spray; flatten to 3/4-inch thickness.
Bake at 350° for 25 minutes. Remove roll from baking sheet; cool 10 minutes on a wire rack. Cut roll diagonally into 20 (1/2-inch) slices. Place, cut sides down, on baking sheet. Reduce oven temperature to 325°. Bake 10 minutes; turn biscotti over, and bake an additional 10 minutes (cookies will be slightly soft in center but will harden as they cool). Remove from baking sheet; cool completely on wire rack.