Preheat your oven to 325°F (160°C). In a mixing bowl, combine crushed vanilla wafers, granulated sugar, and melted unsalted butter. Blend until the mixture resembles wet sand, then press it firmly into the bottom of a 9-inch springform pan. Bake the crust for 10 minutes until lightly golden, then remove from the oven and allow to cool completely.

In a large mixing bowl, beat softened cream cheese using a hand mixer or stand mixer on medium speed until smooth and creamy. Gradually add sugar, mix until fully incorporated. Then, mix in the mashed ripe bananas, adding each egg one at a time, followed by vanilla extract and sour cream.

With the mixer on low speed, carefully sprinkle in the all-purpose flour. Mix just until combined. The batter should be smooth and silky.

Pour the cheesecake filling into the cooled crust, spreading it evenly with a spatula. Bake for 55-65 minutes until set around the edges. Turn off the oven and let the cheesecake cool inside for 1 hour.

Prepare the topping by combining crushed vanilla wafers and chopped pecans with melted butter in a clean bowl. Mix until crumbs are evenly coated.

Once the cheesecake has cooled to room temperature, evenly distribute the topping mixture over the surface. Press gently to adhere to the cheesecake.

Refrigerate the cheesecake for at least 4 hours, preferably overnight. Consider adding fresh banana slices or a caramel drizzle before serving.