Make the pudding base: In a medium saucepan off the heat, whisk together sugar, cornstarch, and salt. Add the egg yolks and a splash of milk, whisking until smooth. Slowly whisk in the remaining milk until no lumps remain.

Cook until thick: Set the pan over medium heat. Whisk constantly as the mixture heats, making sure to reach the corners of the pan. Once it begins to bubble, continue whisking for 1–2 minutes until thick and glossy.

Finish the custard: Remove from heat. Whisk in butter and vanilla until fully incorporated. Transfer to a bowl and press plastic wrap directly on the surface to prevent a skin. Let it cool to room temperature, then chill 20–30 minutes so it’s slightly cool but still spreadable.

Prep the bananas: Slice bananas just before layering to keep them fresh-looking. Aim for 1/4-inch slices for even layers.

Layer the dessert: In a 9x13-inch dish or a large trifle bowl, add a layer of cookies. Top with a layer of banana slices. Spoon over a third of the pudding and spread gently. Repeat for two more layers: cookies, bananas, pudding. End with pudding on top.

Add the topping: Whip the heavy cream with powdered sugar and vanilla to medium peaks, then spread over the pudding. Or use thawed whipped topping for convenience. Lightly dust with cinnamon if you like.

Chill: Cover and refrigerate at least 4 hours, ideally overnight. This lets the flavors meld and the cookies soften to the perfect cake-like texture.

Serve: Scoop into bowls or slice into squares. Garnish with extra banana slices or crushed cookies just before serving.