In a mixing bowl, combine graham cracker crumbs, melted butter, sugar, and a pinch of salt. Stir until the mixture resembles damp sand. Press into mini tart pans and refrigerate for at least 30 minutes.

Heat milk in a saucepan over medium heat until steaming. In a bowl, whisk together sugar, cornstarch, and salt. Temper egg yolks with hot milk, then whisk back into saucepan. Cook until thickened, about 5-7 minutes.

Remove pot from heat, stir in butter and vanilla extract. Allow filling to cool slightly, then refrigerate for 30 minutes.

Slice bananas and arrange them in the chilled crusts. Pour cooled filling over bananas and smooth the top. Refrigerate for at least 1 hour to set.

Whip heavy cream and powdered sugar in a bowl using an electric mixer until soft peaks form, about 3-5 minutes.

Top each pie with whipped cream and garnish with additional banana slices or optional toppings. Serve chilled.