In a bowl, whisk milk and pudding mix for 2 minutes. Let stand for 2 minutes or until soft-set. Stir in sour cream until smooth. Fold in 1-1/2 cups whipped topping.
Place half of the banana slices in the crust; top with half of the pudding mixture. Repeat layers. Spread with remaining whipped topping. Refrigerate for 4-6 hours before serving (pie will be soft- set). Refrigerate leftovers.