In a large bowl, whisk together the pudding mix and milk until thick and smooth.
Stir in the sweetened condensed milk and vanilla extract until fully combined.
Gently fold in the whipped topping until the pudding is silky and uniform.
In a serving dish, layer Nilla wafers on the bottom, followed by banana slices, then pudding.
Repeat the layers until the dish is full, finishing with a final layer of pudding on top.
Cover and refrigerate for at least 4 hours, preferably overnight, to allow the flavors to meld and the wafers to soften.
Serve chilled and enjoy every creamy, nostalgic bite.