Make the Graham Crust:

1. Preheat oven to 325°F (163°C).
2. In a medium bowl, mix vanilla wafer crumbs, melted butter, and sugar until the texture resembles wet sand.
3. Press the mixture evenly into the bottom of a 9-inch springform pan.
4. Bake for 10 minutes, then set aside to cool. Wrap the pan with foil for a water bath.

2. Prepare the Cheesecake Filling:

1. Lower the oven temperature to 300°F (149°C).
2. In a large mixing bowl, beat cream cheese, sugar, and flour until smooth and creamy.
3. Add sour cream, banana extract, and pureed bananas, mixing until fully incorporated.
4. Beat in eggs one at a time, ensuring each is fully mixed before adding the next.

3. Assemble and Bake:

1. Pour the cheesecake mixture into the prepared crust.
2. Place the springform pan inside a larger pan. Fill the outer pan with hot water halfway up the sides of the springform pan to create a water bath.
3. Bake for 90 minutes or until the edges are set and the center jiggles slightly.
4. Turn off the oven and let the cheesecake sit inside with the door closed for 30 minutes.
5. Crack the oven door open and allow the cheesecake to cool for another 30 minutes before removing it.
6. Cool completely at room temperature, then refrigerate.

4. Make the Bavarian Cream:

1. Sprinkle powdered gelatin over milk and let bloom for 5 minutes.
2. In a saucepan, heat heavy cream, sugar, vanilla extract, and banana extract until warm.
3. Temper egg yolks by adding a small amount of the warm cream mixture, then return it to the saucepan.
4. Cook over low heat, stirring constantly, until thickened. Stir in bloomed gelatin until fully dissolved.
5. Cool mixture over an ice bath until slightly thickened.
6. Whip cold heavy cream and powdered sugar to stiff peaks, then fold into the cooled mixture.
7. Spread Bavarian cream over the cooled cheesecake. Refrigerate for 5-6 hours or until set.

5. Prepare the Topping:

1. Whip heavy whipping cream, powdered sugar, and vanilla extract to stiff peaks.
2. Pipe or spread whipped cream over the cheesecake.
3. Garnish with fresh banana slices before serving.