Give me a banana cream pie recipe

Ingredients:

- 1 pre-made pie crust
- 3 ripe bananas
- 1 cup granulated sugar
- 1/4 cup cornstarch
- 1/2 teaspoon salt
- 2 cups whole milk
- 4 egg yolks
- 1 teaspoon vanilla extract
- 2 tablespoons unsalted butter
- 1 cup heavy cream
- 2 tablespoons powdered sugar

Instructions:
1. Preheat oven to 375°F (190°C) and bake the pre-made pie crust according to package instructions. Set aside to cool.
2. In a medium saucepan, mash the bananas with a fork until smooth.
3. In a separate bowl, whisk together the sugar, cornstarch, and salt. Gradually whisk in the milk until smooth.
4. Add the milk mixture to the saucepan with the bananas and stir constantly over medium heat until the mixture thickens and comes to a boil.
5. In a small bowl, whisk the egg yolks. Gradually add a small amount of the hot banana mixture to the egg yolks, whisking constantly to temper the eggs.
6. Pour the egg mixture back into the saucepan with the banana mixture and cook for an additional 2 minutes, stirring constantly.
7. Remove from heat and stir in the vanilla extract and butter until smooth. Pour the filling into the baked pie crust and refrigerate for at least 2 hours.
8. In a separate bowl, whip the heavy cream with powdered sugar until stiff peaks form. Spread the whipped cream over the pie just before serving.
9. Enjoy your delicious banana cream pie!