Peel and Slice: Begin by peeling the bananas and slicing them into even round slices. Set aside.
Mixing the Ingredients: In a microwave-safe bowl, combine sugar, cornstarch, and a pinch of salt. Gradually whisk in milk, ensuring there are no lumps.
Microwave: Place the bowl in the microwave and heat on high for 5 minutes, stopping every minute to stir the mixture.
Add Final Touches: Once thickened, remove from the microwave and stir in butter and vanilla extract until the butter is fully melted.
Layering: In serving glasses or bowls, create alternate layers of vanilla wafer cookies, banana slices, and the pudding mixture.
Chill: Refrigerate the pudding for at least an hour or until set.