In the body of a stand mixer with the whisk attachment, mix the condensed milk with the water until combined. Add the vanilla pudding and vanilla extract, mix until combined. This mixture will be very runny. Pour it into a medium-sized bowl, cover with plastic wrap and place it in the fridge for at least 2 hours or overnight until firm.
Once you are ready to assemble the pudding, whip the heavy cream in the body of a stand mixer with the whisk attachment until it forms stiff peaks, do not overmix.
With the mixer on low, start adding spoonfuls of the firm pudding mixture to the cream. Mix until there are no streaks of pudding or whipped cream.
Thinly slice the bananas right before you are ready to assemble.
Reserve 5 cookies for the topping.
Add 1/4 of the pudding to the bottom of a 4-5 quart trifle bowl. Add ⅓ of the remaining cookies on top. Add ⅓ of the sliced bananas over the cookies. Repeat two more times, topping the entire thing with the remaining pudding.
Cover and place in the fridge for 2-4 hours so the flavors can combine. Garnish with the leftover cookies and serve.