In a medium bowl, combine the graham cracker crumbs, melted butter, and 3 tablespoons of granulated sugar. Mix until the mixture resembles wet sand.

Press the crumb mixture firmly into the bottoms and up the sides of mini tart pans or a mini muffin tin lined with paper cups. Chill in the refrigerator for at least 30 minutes to set.

While the crust chills, slice the bananas into thin rounds and set aside.

In a medium saucepan, whisk together the egg yolks, ½ cup sugar, and cornstarch until smooth.

Slowly add the milk to the egg mixture, whisking constantly to avoid lumps. Cook over medium heat, stirring continuously until it thickens and begins to bubble, about 5-7 minutes. Remove from heat and stir in vanilla extract.

Transfer the custard to a bowl, cover with plastic wrap directly on the surface to prevent a skin from forming, and let it cool to room temperature.

Once cooled, gently fold the sliced bananas into the custard, reserving a few slices for topping.

In a separate bowl, whip the heavy cream with powdered sugar until stiff peaks form.

Fold half of the whipped cream into the banana custard mixture to lighten it.

Spoon the creamy filling into each chilled crust, then top with the remaining whipped cream and a banana slice for garnish.

Refrigerate the mini pies for at least 2 hours before serving.