Combine graham cracker crumbs, melted butter, and sugar in a bowl until it resembles wet sand. Press into a pie dish firmly and bake at 350°F for 10-12 minutes until lightly golden, or freeze for a no-bake option.

In a saucepan, whisk together sugar, cornstarch, and a pinch of salt with eggs. Gradually add in whole milk and cook over medium heat, stirring constantly until thickened.

Strain the mixture, then mix in vanilla and butter until smooth.

Fold in sliced bananas to the warm pudding gently and pour into the prepared pie crust, smoothing the top. Allow to cool at room temperature before refrigerating for at least 3 hours.

Using an electric mixer, whip heavy cream until soft peaks form. Gradually add sugar and vanilla, and continue whipping until desired peaks are achieved. Pipe or spread over the chilled pudding before serving.

Optionally, garnish with extra banana slices or crushed graham cracker on top. Serve chilled for best flavor.