In a medium bowl, whisk together 2 cups of cold milk, 1 can of sweetened condensed milk, and 1 package of instant vanilla pudding mix until smooth. Cover with plastic wrap and refrigerate for at least 15 minutes to set.

In a large mixing bowl, pour 2 cups of heavy whipping cream and beat with an electric mixer until firm peaks form, which takes about 3-5 minutes.

Gently fold the chilled pudding mixture into the whipped cream using a spatula until fully combined.

Spread half of the pudding mixture evenly across the bottom of a 9x13" dish.

Slice 4 ripe bananas into ¼" thick coins and layer about ¾ of the banana slices over the pudding.

Crumble 18 Biscoff cookies finely and sprinkle them over the banana layer.

Pour the remaining pudding mixture over the crumbled cookies and banana layers, spreading it evenly.

Garnish with reserved banana slices and any remaining crumbled Biscoff cookies before serving. Chill for at least 2 hours.