Make the pie crust:

1. Preheat oven to 425F.
2. If using homemade pie dough, roll it out to be about 12 inches in diameter. Transfer the rolled dough into a 9-inch pie plate, and finish by fluting or crimping the edges.
3. Place a crumpled piece of parchment inside. Fill it with pie weights or dried beans.
4. Place onto a baking sheet and into the oven to bake for 15 minutes.
5. Remove the pie crust from the oven and carefully remove the parchment and weights.
6. In a small mixing bowl, whisk together the egg and water. Brush the pie with the egg wash.
7. Use a fork to prick the crust all over. Return to the oven to bake for another 10 minutes. After 10 minutes, turn the oven down to 375°F, and bake for 15 more minutes. Finally, remove from the oven, and allow the crust to cool completely.

Make the banana cream pie filling:

1. In a large mixing bowl, add the egg yolks, sugar, milk, heavy cream, and cornstarch, and whisk together until very smooth.
2. Place a sieve over a medium saucepan and pour the custard mixture over the sieve into the saucepan.
3. Place the saucepan on the stove and heat over medium heat. While whisking constantly, bring the custard up to a simmer, then continue to cook until the custard has thickened like pudding, and begins bubbling and popping. Once bubbling, continue to stir and cook for exactly one more minute.
4. Immediately remove from the heat, and stir in the butter cubes, vanilla, and salt.
5. Place a sieve over top of a large mixing bowl, and pour the custard over the sieve to remove any lumps.
6. Place a piece of plastic wrap over the surface of the custard and transfer to the fridge to cool to around room temperature.

Make the whipped cream:

1. Place the heavy cream, confectioners’ sugar, and vanilla into a large mixing bowl. Beat with a whisk or an electric hand mixer until stiff peaks have formed. Cover and set aside in the fridge for later.
2. Assemble the banana cream pie
3. Once the custard is at room temperature, spread a thin layer of the custard onto the bottom of the cooled pie crust. Add a layer of sliced bananas, then top with remaining custard.
4. Smooth out the custard, cover the surface with plastic wrap, then place into the fridge to fully cool – at least 4 hours but preferably overnight.
5. At serving time, add the whipped cream on top of the custard, then top with more sliced bananas right before serving.