Prep your dish: Use a 2–2.5 quart baking dish or trifle bowl. Set aside.

Make the custard base: In a medium saucepan off the heat, whisk together sugar, cornstarch, and a pinch of salt. Add milk and cream, whisking until smooth.

Temper the eggs: In a separate bowl, whisk the egg yolks. Place the saucepan over medium heat and cook, whisking constantly, until the mixture is steaming and slightly thickened, about 4–5 minutes. Slowly ladle some hot mixture into the egg yolks while whisking, then pour the egg mixture back into the pot.

Cook until thick: Continue whisking over medium heat until the pudding thickens and gently bubbles, 2–4 minutes. It should coat the back of a spoon.

Finish the pudding: Remove from heat. Stir in butter and vanilla until smooth. Let it cool for 10 minutes, stirring occasionally to prevent a skin from forming.

Layer the dessert: Place a single layer of vanilla wafers on the bottom of your dish. Add a layer of sliced bananas. Spoon a generous layer of warm pudding over the bananas, spreading to the edges.

Repeat: Continue layering wafers, bananas, and pudding until you run out, ending with a layer of pudding on top.

Add topping: Spread whipped cream over the chilled pudding or, if using meringue, whip egg whites with cream of tartar to soft peaks, gradually beat in sugar to stiff glossy peaks, and spread over the warm pudding, sealing to the edges.

Optional meringue bake: If using meringue, bake at 350°F (175°C) for 10–12 minutes, until lightly golden. Cool to room temperature.

Chill: Cover and refrigerate at least 4 hours (overnight is best) so the flavors meld and the wafers soften.

Garnish and serve: Top with crushed wafers or banana slices just before serving. Scoop and enjoy.