1. Preheat the oven to 425ºF.
2. Roll out your pie dough and line a 9-inch pie pan. Prick the dough all over with a fork. Line the pie crust with parchment paper and fill with pie weights.
3. Bake the pie crust in the preheated oven for 20 minutes, then remove the pie weights and parchment paper and bake for another 10 minutes. The crust should be golden brown. Set aside to cool before filling.

For the Filling:

1. Combine milk and vanilla in a saucepan over medium heat. Cook until just simmering, about 10 minutes, stirring very frequently to milk doesn’t scald. 
2. While the milk is cooking, add egg yolks, sugar, and salt to a large mixing bowl. Whisk together until smooth.
3. Add the cornstarch to the egg mixture and whisk again until it is all incorporated. The mixture will be light yellow and thick like paste.
4. Once the milk has cooked, pour a small amount of hot milk into the egg mixture while whisking to avoid cooking the eggs.
5. Continue to add the milk a little at a time, mixing well between each addition, until all of the milk has been added.
6. Return the egg and milk mixture to the saucepan.
7. Cook over medium heat, whisking constantly, until the mixture thickens to a pudding-like texture, about 3 minutes. Continue to cook the cream mixture for another 2 minutes to set the starch. Stir constantly to prevent burning.
8. Remove from the heat and stir in the butter until melted.
9. Set the filling aside to cool for 15 minutes.

Assemble the Pie:

1. Line the bottom of the pie crust with coins of banana sliced 1/4- inch thick.
2. Spread the cream filling over the bananas, making sure to completely cover all of the fruit to prevent browning.
3. Place a piece of plastic wrap on top of the cream and press it into the surface to form a good seal.
4. Refrigerate the pie for at least 4 hours, but overnight is better.
5. Immediately before serving, top with whipped cream and additional banana slices.