Heat oven to 350°F. Lightly grease cookie sheet. In large bowl, combine sugar and butter; beat until light and fluffy. Add vanilla and eggs; blend well. Add flour, cocoa and baking powder; mix well. Stir in toasted hazelnuts and chocolate chips.
Divide dough in half; shape each into 10-inch log. Place logs 5 inches apart on greased cookie sheet; flatten each until 3 inches wide.
Bake at 350°F. for 20 to 25 minutes or until firm when touched in center. Cool on cookie sheet for 10 minutes. With serrated knife, cut diagonally into 1/2-inch slices. Arrange slices, cut side down, on same cookie sheet.
Return to oven; bake 10 minutes. Turn slices over; bake an additional 5 to 10 minutes or until cut sides are lightly browned and crisp. Remove from cookie sheet; place on wire rack. Cool 10 minutes or until completely cooled.
Place candy coating in small microwave-safe bowl. Microwave on HIGH for 45 seconds, stirring once, or until melted and smooth. If necessary, microwave an additional 20 seconds. Drizzle over biscotti.