Whisk the banana pudding mix with cold milk in a large bowl until smooth and thickened.
In a separate bowl, fold half of the Cool Whip into half of the prepared banana pudding to create a lighter creamy layer.
Mix graham cracker crumbs, sugar, and melted butter until combined; press into the bottom of an 8x8 inch baking dish to form the crust.
Spread a layer of plain banana pudding over the graham cracker crust.
Arrange a layer of whole graham crackers over the pudding, breaking them to cover the surface as needed.
Spread the banana pudding and Cool Whip mixture over the graham cracker layer.
Add another layer of graham crackers on top.
Evenly spread the remaining Cool Whip over the top graham crackers.
Cover with plastic wrap and refrigerate for at least 4 hours or overnight to soften crackers and meld flavors.
Before serving, top with freshly sliced bananas, slice, and enjoy.