Step 1: Whisk the Pudding Base: In a large mixing bowl, combine the instant pudding mix and cold milk. Whisk vigorously for about two minutes until the mixture begins to thicken. Stir in the sweetened condensed milk and vanilla extract until the base is completely smooth.
Step 2: Fold in the Cream: Gently fold in half of the thawed whipped topping (or homemade whipped cream) into the pudding mixture. Use a spatula to turn the mixture over on itself until no white streaks remain. This creates a light, mousse-like texture for your trifle.
Step 3: Prepare the First Layer: Take a large glass trifle bowl and place a single layer of vanilla wafer cookies at the very bottom. You can also stand some cookies up against the side of the glass for a decorative look. Add a layer of sliced bananas on top of the cookies.
Step 4: Add the Pudding Layer: Spread about one-third of the pudding mixture over the banana layer. Use the back of a spoon to smooth it out to the edges of the bowl, ensuring it covers the cookies and bananas completely.
Step 5: Repeat the Layers: Continue layering with more vanilla wafers, followed by more banana slices, and another portion of the pudding. Repeat this process until you reach the top of the bowl or run out of ingredients, ending with a layer of pudding.
Step 6: Top and Chill: Spread the remaining whipped topping over the final pudding layer. Garnish the top with a few crushed vanilla wafers or a few fresh banana slices. Cover the bowl with plastic wrap and refrigerate for at least 3 to 4 hours, or ideally overnight, before serving.