Step 1: Prepare the Pudding Base
In a large mixing bowl, whisk together the 14-ounce can of sweetened condensed milk, 1 and 1/2 cups of ice-cold water, and the box of instant vanilla pudding mix until they are well combined. This should take about one minute of whisking.

Step 2: Add the Biscoff Flavor
Melt the 1/2 cup of Biscoff cookie butter in the microwave for 20 seconds to make it pourable. Add the melted cookie butter to the pudding mixture and continue to mix until it is fully incorporated and uniform in color.

Step 3: Whip the Cream
In a separate, large bowl, use a hand mixer or stand mixer to whip the 3 cups of heavy cream until firm, stiff peaks form. The whipped cream should hold its shape when you lift the whisk.

Step 4: Fold and Combine
Gently fold the whipped cream into the Biscoff pudding mixture. Use a large rubber spatula and cut down the middle, then sweep up the side and over the mixture, turning the bowl as you go. Continue this careful folding motion until no streaks of vanilla pudding remain and the mixture is uniformly fluffy.

Step 5: Build the Layers
In your 9×13 dish or trifle bowl, begin the layering process. Start by spreading 1/3 of the prepared Biscoff vanilla pudding mixture across the bottom. Next, top this layer with 16 whole Biscoff cookies and a single layer of fresh banana slices. Repeat this process once more, using another 1/3 of the pudding, 16 cookies, and more banana slices.

Step 6: Finish and Chill
Finish the dessert by spreading the remaining vanilla pudding mixture smoothly over the top layer of bananas and cookies. Cover the dish tightly with plastic wrap and chill it in the refrigerator for a minimum of 3 to 4 hours, or up to 8 hours for maximum firmness.

Step 7: Serve
When you are ready to serve, garnish the top with crushed Biscoff cookie crumbs, fresh banana slices, and a drizzle of extra melted cookie butter (optional).