Preheat the oven to 350°F (175°C). In a mixing bowl, combine graham cracker crumbs, granulated sugar, and melted butter. Mix until well combined. Press the mixture firmly into the bottom and up the sides of a 9-inch pie dish to form a crust.

Bake the crust in the preheated oven for about 10 minutes or until golden brown. Remove from oven and allow to cool completely.

In a saucepan over medium heat, whisk together the milk, granulated sugar, cornstarch, and salt. Cook the mixture while stirring constantly until it starts to thicken and bubble.

In a separate bowl, whisk the egg yolks. Gradually add a small amount of the hot milk mixture to the egg yolks, whisking constantly to temper the eggs. Then, pour the egg yolk mixture back into the saucepan.

Continue to cook, stirring for another 2-3 minutes until the mixture thickens further. Remove from heat and stir in the butter and vanilla extract. Allow the filling to cool slightly.

Once the filling has cooled, layer the sliced bananas into the cooled pie crust. Pour the custard filling over the bananas, spreading it evenly.

Refrigerate the pie for at least 4 hours or until fully chilled and set.

In a mixing bowl, whip the heavy cream, powdered sugar, and vanilla extract until soft peaks form. Spread the whipped cream over the top of the pie before serving.

Slice and enjoy your delicious Banana Cream Pie!