Crush marie biscuits with food processor and combine the crumbs with melted butter. Pour into the 24 cm spring-form pan. Press down the crush mixture on the bottom and the sides of the spring-form pan with hand or a spoon and place it into the fridge.

In a saucepan, combine sugar, cornstarch, and salt. Add in milk and whisk until there is no lump. Heat milk mixture over medium heat, whisk continuously until thickened.

In a small bowl, lightly beat the egg yolk then slowly stir about ¼ cup hot milk mixture into the egg yolk until well combined. Whisk back the egg mixture to a saucepan.

Continue to cook over medium heat for 2 minutes or until thickened. Remove the saucepan from heat, then add butter and vanilla and whisk until well combined.

Transfer the custard cream to a bowl. Cover it with plastic wrap and press it directly onto the surface of the custard cream to prevent it from forming a skin on the surface. Let it cool completely in a refrigerator.

Slice the banana and set aside.

After the custard is cooled, pour about ⅓ of it onto the bottom of the crust, then add a layer of sliced banana, and pour the rest of the custard cream. Smooth out then cover it with plastic wrap and refrigerate for at least 4 hours.

Place cold heavy cream in the bowl and whisk until hard peaks. When ready to serve, add the whipped cream on top of the pie and garnish it with sliced banana. Enjoy!