Place the yolks, sugar, cornstarch, and salt in a medium bowl and whisk to combine.
Heat the milk in a small pot until small bubbles form around the edge, and wisps of steam are rising from the surface.
Add the hot milk to the egg mixture, a little at a time, whisking to combine.
When all the milk has been added, transfer the mixture back to the pot and place over medium-low heat.
Cook the pastry cream, whisking, until thickened. Remove from heat.
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.
Press a layer of plastic wrap directly onto the surface, and refrigerate for 2 hours minimum.
Whip the cream until it holds stiff peaks, and fold it into the pastry cream.
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.
Place another layer of sliced bananas over the filling, and smooth the remaining filling on top.
Garnish with whipped cream and more sliced bananas.
Whipped Topping
Whip the cream and powdered sugar together until it holds soft peaks.
Spread or pipe whipped cream on the pie and garnish with sliced bananas.