Best-Ever Chocolate Fudge Layer Cake

This is my mom's recipe- and it really is the BEST chocolate cake I've ever had.

Best-Ever Chocolate Fudge Layer Cake
1 pkg. (8 squares) Semi-Sweet Baking Chocolate, divided
1 pkg. (2-layer size) chocolate cake mix (I used Devil's Food Cake Mix)
1 pkg. (4-serving size) Jell-O Chocolate Flavor Instant Pudding & PieFilling
4 eggs
1 cup Sour Cream
1/2 cup oil
1/2 cup milk
1 Tub (8 oz.) Cool Whip Whipped Topping


PREHEAT oven to 350 degrees. Grease two 9-inch roundbaking pans. Chop 2 of the chocolate squares; set aside. Beat cake mix, dry pudding mix, eggs, sour cream, oil and milk in large bowl with electric mixer on low speed just until moistened. Beat on medium speed 2 min. Stir in chopped chocolate. Spoon into prepared pans. Bake 30 to 35 min. or until wooden toothpick inserted in centers comes out clean. Cool in pans on wire racks 10 min. 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 microwaveable bowl. Microwave on HIGH 1 1/2 min. or until chocolate is completely melted and mixture is smooth, stirring after 1 min. Let stand 15 min. to thicken. Place 1 cake layer on serving plate; top with 1/4 of the chocolate mixture. Place second layer on top of first, use remaining 3/4 of the chocolate mixture to "frost". Store in refrigerator.