In a large mixing bowl, combine milk, vanilla pudding mix and sweetened condensed milk. Whisk thoroughly, breaking up any lumps, and refrigerate for at least 5 minutes, or until set.

In another large bowl, combine heavy cream and vanilla. Beat until stiff peaks form, 2 to 3 minutes. Set aside half of the mixture for topping the dish. Fold remaining half into the pudding mixture.

Cover the bottom of a 3-quart trifle dish with vanilla wafers. Top with one-third of the pudding mixture. Cover with another layer of the wafer cookies—you may want to also stand some cookies up vertically, so you see the full circle along the edge of the trifle dish. Top with an even layer of banana slices. Continue layering the pudding, wafer cookies and banana slices until you reach the top, ending with a final layer of banana pudding.

Refrigerate for at least 3 hours, or up to overnight.

Sweeten the remaining whipped cream: Add sugar to whipped cream, stirring to combine. Just before serving, dollop on top of the banana pudding, then sprinkle crumbled wafer cookies on top.