Preheat the oven to 350°F (175°C).
In a mixing bowl, combine graham cracker crumbs, sugar, and melted butter. Mix until well combined.
Press the mixture firmly into the bottom and sides of a 9-inch pie pan.
Bake for 10 minutes, then remove from oven and let cool completely.
In a saucepan over medium heat, combine milk, sugar, cornstarch, and salt. Whisk until smooth and cook until slightly thickened.
In a separate bowl, whisk the egg yolks. Slowly add a small amount of the hot milk mixture to the yolks while whisking continuously.
Pour the egg mixture back into the saucepan and continue cooking over medium heat until thickened, about 3 minutes.
Remove from heat and stir in white chocolate and vanilla extract until smooth.
Place sliced bananas in the cooled pie crust and pour the white chocolate custard over them, smoothing the top.
Chill in the refrigerator for at least 4 hours or until set.
In a mixing bowl, beat the heavy whipping cream and powdered sugar until stiff peaks form.
Spread or pipe whipped cream over the chilled pie before serving.