Best-Ever Chocolate Fudge Layer Cake

1 pkg (8 squares) Baker's Semi-Sweet Baking Chocolate, divided
1 pkg. (2-layer size) chocolate cake mix
1 pkg. (4 serving size) Jell-O Chocolate Flavor Instant Pudding & Pie Filling
4 eggs
1 cup sour cream
1/2 cup oil
1/2 cup water
1 tub (8 oz) frozen Cool Whip Whipped Topping

Preheat oven to 350°. 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 large bowl with electric mixer on low speed untilo just moistened. Beat on medium speed 2 minutes. Stir in 2 squres chopped chocolate. Spoon into prepared pans.

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

Place frozen whipped topping and remaining 6 chocolate squares in microwavable bowl. Microwave on high 1 1/2 minutes or until chocolate is completely melted and mixture is smooth, stirring after one minute. Let stand 15 minutes to thicken. Place 1 cake layer on serving plate; top with 1/2 of the chocolate mixture and the second cake layer. Spread to and side with remaining chocolate mixture. Store in refrigerator.