**Prepare the pudding**
In a mixing bowl, whisk together the pudding mix and cold milk for 2 minutes, or until the mixture is smooth and begins to thicken. Let it sit for 5 minutes to fully set.
**Layer the trifle**
In the bottom of a trifle dish or individual serving cups, add a layer of vanilla wafers. Top with a layer of sliced bananas, followed by a layer of vanilla pudding. Spread a layer of whipped topping over the pudding.
**Repeat the layers**
Repeat the layers (vanilla wafers, bananas, pudding, whipped topping) until all the ingredients are used, finishing with a layer of whipped topping on top.
**Garnish**
Decorate the top of the trifle with crushed vanilla wafers, a drizzle of caramel, or additional banana slices if desired.
**Chill**
Cover the trifle with plastic wrap and refrigerate for at least 2 hours, or overnight, to allow the flavors to meld together.
**Serve**
Serve chilled with a large spoon for scooping or as individual portions.