Set up your dish. Choose a 2–3 quart dish or a clear trifle bowl. It helps to see the layers.
Keep your cookies and sliced bananas ready to go before you start the pudding.
Slice the bananas. Cut them into 1/4-inch rounds. If you want to prevent browning, toss them lightly with a squeeze of lemon juice. Set aside.
Make the custard base. In a medium pot, whisk together sugar, cornstarch, and a pinch of salt.
Slowly whisk in the milk until smooth. Set over medium heat, stirring constantly.
Thicken carefully. Keep whisking as the mixture warms. When you see gentle bubbles and the pudding thickens to a loose yogurt consistency, remove from heat.
Temper the egg yolks. In a bowl, whisk the yolks.
Slowly stream in 1/2 cup of the hot milk mixture while whisking. Return this to the pot and cook over low heat, whisking, for 1–2 minutes until silky and thick. Don’t let it boil hard.
Finish with butter and vanilla. Off the heat, whisk in butter and vanilla.
Taste for sweetness and salt. The pudding should be smooth and pourable, not stiff.
Build the first layer. Line the bottom of your dish with vanilla wafers. They don’t need to be perfect—just cover the surface.
Add bananas. Arrange a single layer of banana slices over the cookies.
Don’t stack too high or the layers can slide.
Pour the pudding. Spoon a warm layer of pudding over the bananas. Use just enough to cover and seep between gaps.
Repeat layers. Continue with cookies, bananas, and pudding until you reach the top. End with a generous layer of pudding so the bananas aren’t exposed to air.
Chill to set. Cover and refrigerate for at least 4 hours, or overnight for softer, cake-like cookies.
Whip the cream. Beat heavy cream with powdered sugar to soft peaks.
Spread or dollop over the chilled pudding before serving.
Optional meringue. For a classic Southern touch, whip egg whites with sugar to stiff peaks and spoon on top. Torch or broil briefly until golden. Serve the same day.
Finish and serve. Sprinkle with crushed cookies or a pinch of cinnamon if you like.
Serve cold for the cleanest slices.