To prepare pudding layer, add pudding mix and milk to a large mixing bowl. Whisk mixture until it thickens.
Add half of whipped topping to pudding mixture. Blend well until uniform.
Create one layer of graham crackers in the bottom of a 9x13-inch baking dish. You may have to break them to make them fit.
Spread ⅓ of pudding mixture on top of graham crackers. Continue this process until you have four layers of graham crackers and three layers of the pudding mixture.
Finish things off by spreading the remaining whipped topping to cover the graham crackers.
Cover dessert with plastic wrap and refrigerate for at least 6 hours.
Slice, garnish with crushed graham crackers and sliced bananas, and enjoy!
Notes
Adjust the Crunch Level: The longer you let this icebox cake sit in the fridge, the softer the graham crackers will get. If you prefer a softer, moister crust, you can let it sit for a few more hours or overnight to get the results you want.
Use Ripe Bananas: Ripe bananas are the best for this dessert, as they will continue to ripen and soften over time. Overripe bananas will become mushy too quickly.
Layer Evenly: Try your best to create even layers for the best consistent texture and flavor in every bite.
Chill Thoroughly: Refrigerating for at least 6 hours is key. It gives the pudding time to set and the graham crackers time to soften, so you get that perfect, cake-like texture.
Use Instant Pudding Only: Be sure to use instant banana pudding mix—not cook-and-serve. Instant pudding sets quickly and is ideal for layering.
Wait to Garnish with Bananas: Add fresh banana slices just before serving to prevent browning and keep the dessert looking fresh.