Preheat oven to 350ºF. Grease two 9-inch round baking pans. Chop 2 of the chocolate squares; set aside. Beat cake mix, dry pudding mix, eggs, sour cream, oil and water in a large bowl with an electric mixer on low speed just until moistened. Beat on medium speed for 2 minutes. Stir in the chopped chocolate. Batter will be very thick. Spread into prepared pans.

Bake for 30-35 minutes or until a wooden toothpick inserted in the centers comes out clean. Cool in pans on wire racks for 10 minutes. Loosen cakes from the sides of the pans. Invert onto wire racks; gently remove pans and cool cakes completely.

For the frosting: chop remaining 6 chocolate squares. Place chocolate in a microwave safe bowl with all of the frozen whipped topping. Microwave on high for 1 1/2 minutes or until chocolate is completely melted and mixture is smooth, stirring after 1 minute. Let stand for 10-15 minutes to thicken. Place 1 cake layer on a serving plate; top with 1/4 of the chocolate mixture and the second cake layer. Spread the top and sides with the remaining chocolate mixture.

Chocolate curls: melt a bag of chocolate chips and spread in this layer on a large cookie sheet. Let it cool until it is set. Scrape the chocolate off with the edge of a knife or edge of a metal spatula to form curls.