1. Place the yolks, sugar, cornstarch, and salt in a medium bowl and whisk to combine.
2. Heat the milk in a small pot until small bubbles form around the edge, and wisps of steam are rising from the surface.
3. Add the hot milk to the egg mixture, a little at a time, whisking to combine.
4. When all the milk has been added, transfer the mixture back to the pot and place over medium-low heat.
5. Cook the pastry cream, whisking, until thickened.
6. Stir in the vanilla, and pour the pastry cream through a fine mesh strainer, into a heat-safe bowl. Use the back of a ladle to press the mixture through the sieve.
7. Press a layer of plastic wrap directly onto the surface, and refrigerate for 2 hours minimum.
8. Whip the cream until it holds stiff peaks, and fold it into the pastry cream.
9. Line the bottom of the pre-baked pie crust with slices of fresh banana, and spread half the filling on top in an even layer.
10. Place another layer of sliced bananas over the filling, and smooth the remaining filling on top.
11. Garnish with whipped cream and more sliced bananas.
12. Combine the flour and salt in a large bowl.
13. Add the oil, and stir until the mixture resembles coarse meal.
14. Cut the butter into thin slices and toss in the flour mixture to coat.
15. Dribble ice water in, a tablespoon at a time, mixing just until the mixture can hold its shape.
16. Gather the dough into a ball, and shape into a disk. Wrap tightly in plastic wrap, and refrigerate for at least an hour.
17. Roll the dough out to thickness, and fold into thirds. Fold into thirds again, then one more time, and refrigerate for another hour.
18. Preheat the oven to 375 degrees F.
19. Unwrap the dough and roll to about two inches larger than the diameter of your pie plate.
20. Slip the dough into the ungreased pie plate, and prick with a fork.
21. Fill the unbaked pie shell with ceramic pie weights or dry beans, and bake for 32 to 38 minutes, or until golden.
22. Cool completely before filling.
23. Whip the cream and powdered sugar together until it holds soft peaks.
24. Transfer the mixture to a piping bag fitted with a 1M open star tip.
25. Pipe swirls of whipped cream around the edge of the pie and garnish with sliced bananas.