Prepare pudding according to box instructions.
Arrange a layer of wafers (19) on the bottom of an 8" springform, dipping each cookie in milk before adding to the pan. Spread a third of the pudding on top of wafers. Arrange a layer of bananas on top of pudding. Top with a third of the Cool Whip. Repeat 2 more times.
Smooth top of cake with a spatula. Cover with plastic and place pan in freezer until firm, about 4 hours.
Unmold and place dollops of Cool Whip around the cake and alternate standing up Nilla wafers and banana slices in the dollops.