01 - In a large mixing bowl, whisk together cold milk and instant vanilla pudding mix for 2 minutes until dissolved. Let the mixture stand for 5 minutes to thicken.
02 - Stir the sweetened condensed milk into the thickened pudding until completely smooth and well incorporated.
03 - In a separate chilled bowl, whip 1 cup heavy cream until soft peaks form. Gently fold the whipped cream and vanilla extract into the pudding mixture until no streaks remain.
04 - Arrange a single layer of Biscoff cookies in the bottom of a trifle dish or 9x13-inch baking dish, breaking cookies as needed to fit.
05 - Top the cookie layer with half of the banana slices, arranging them evenly. Spread half of the pudding mixture over the bananas.
06 - Repeat with remaining cookies, bananas, and pudding mixture, creating distinct layers. Smooth the top surface with a spatula.
07 - Cover tightly with plastic wrap and refrigerate for at least 4 hours, preferably overnight, to allow cookies to soften and flavors to meld.
08 - Whip the remaining 1 cup heavy cream with powdered sugar and 1/2 teaspoon vanilla extract until stiff peaks form. Spread or pipe decoratively over the chilled pudding.
09 - Sprinkle crushed Biscoff cookies over the top. Add fresh banana slices if desired. Serve cold and enjoy within 24 hours.