Peel and Slice Bananas into 1" pieces.
Chill until served.
In a large bowl with a mixer, mix milk into pudding mix, on low speed with a hand mixer.
Add in vanilla extract.
Mix in sweetened condensed milk, continue to mix well until combined.
Set aside hand mixer.
FOLD 12 oz tub of Cool Whip into pudding with a spatula. Do not use mixer.
In a large trifle bowl, put in one layer of wafers, one flat layer of banana slices and top it with a layer of pudding.
Repeat these layers until ingredients are finished. For an attractive look, use a clear bowl and add some "vertical" wafers.
On top, add last layer of cool whip on top... typically some or most of an 8oz. tub will do.