Add the milk to a small bowl, and sprinkle the gelatin on top, set aside.
In a medium bowl, whisk the egg yolks together and set aside.
Add the 1 cup of room temperature heavy cream, white sugar, and banana extract to a large saucepan and heat over medium heat until warm.
Once warm, remove from heat and slowly pour the hot cream into the egg yolks, stirring, to temper them.
Next, add the egg mixture to the saucepan and return to the heat. Cook over medium heat, stirring, until the mixture is thick enough to coat the back of a spoon. That will take only a few minutes.
Add the gelatin mixture to the saucepan and stir until smooth.
Prepare a large bowl filled with add, and pour the hot custard into another smaller bowl, set it over the bowl with ice to cool to room temperature.
Add the 1/2 cup of cold heavy whipping cream and powdered sugar to a large bowl and whisk on high speed until stiff peaks form.
When the custard has fully cooled, gently fold the prepared whipped cream into the custard.
Remove the foil wrapping from the cheesecake, and spread the bavarian cream evenly on top of the cheesecake. Place in the fridge to cool for at least 6 hours.