2 (3.4 oz.) pkg. vanilla instant pudding
3 c. milk
1 (8 oz.) container sour cream
1 (12 oz.) Cool Whip, thawed and divided
6 bananas, sliced
vanilla wafers

Whisk together pudding mix and milk in a large bowl until thickened. Whisk in sour cream; fold in 4 1/2 ounces whipped topping. Layer half of vanilla wafers, sliced bananas and pudding mixture in a 4-quart bowl. Repeat layers. Top with remaining whipped topping. Cover and chill.