Bake the crust: If using a raw pastry shell, blind-bake it until golden and fully set. Let it cool completely. A cooled crust keeps the custard from melting or getting soggy.

Prep bananas: Slice bananas 1/4-inch thick. If you’re worried about browning, toss lightly with a tiny squeeze of lemon juice. Pat dry to avoid extra moisture.

Start the custard: In a medium saucepan, whisk sugar, cornstarch, and a pinch of salt. Gradually whisk in milk until smooth. This dissolves the cornstarch and prevents lumps.

Temper the eggs: In a separate bowl, whisk egg yolks. Heat the milk mixture over medium, whisking, until steaming and slightly thickened. Slowly whisk a ladle of hot milk into the yolks, then return the yolk mixture to the saucepan.

Cook until thick: Continue cooking over medium heat, whisking constantly, until the custard bubbles and thickens to a pudding-like consistency, about 2–4 minutes after the first simmer. Remove from heat and whisk in butter and vanilla.

Cool slightly: Transfer custard to a bowl. Press plastic wrap directly on the surface to prevent a skin. Let it cool 10–15 minutes until warm but not hot.

Assemble the layers: Spread a thin layer of custard in the cooled crust. Add a layer of bananas. Repeat, finishing with custard on top. Smooth the surface. This layering keeps bananas in place and creates even slices.

Chill to set: Cover and refrigerate at least 4 hours, preferably overnight. The custard firms up and flavors meld.

Make the whipped cream: Beat cold heavy cream with powdered sugar to soft peaks. For extra stability, bloom gelatin in water, melt briefly, cool, then stream into the cream as you whip to medium peaks. Alternatively, add instant pudding mix while whipping.

Top and garnish: Spread or pipe the whipped cream over the chilled pie. Garnish with banana slices (just before serving), toasted coconut, chocolate shavings, or crushed wafers.

Slice neatly: Use a sharp, thin knife. Wipe the blade between cuts for clean slices. Serve chilled.