In a large bowl, whisk together the sweetened condensed milk, water, and milk until smooth.
Sprinkle in the vanilla banana pudding mix and whisk until fully combined. Refrigerate for 5–10 minutes to let it set slightly.
In a separate bowl, add the heavy cream and vanilla extract. Whip until stiff peaks form.
Gently fold the whipped cream into the pudding mixture until smooth and fluffy.
In a 9×9-inch (or similar) pan, start with a layer of Nilla wafers. Crush some wafers for added texture, then add a layer of sliced bananas. Spread a portion of the pudding mixture on top. Repeat the layers until the pan is filled, finishing with a layer of pudding on top.
Garnish with extra Nilla wafers, sliced bananas, and chess cookies if desired.
Refrigerate for at least 4 hours (or overnight) to let the flavors meld. Serve chilled and enjoy!