Prepare the Crust
Preheat the oven to 325°F (160°C). In a medium bowl, mix the crushed vanilla wafers, sugar, and melted butter until well combined. Press the mixture firmly into the bottom of a 9-inch springform pan to create an even crust layer. Bake for 10 minutes, then set aside to cool.

Make the Cheesecake Filling
In a large mixing bowl, beat the softened cream cheese until smooth and creamy. Gradually add the sugar, beating until fully incorporated. Mix in the mashed bananas, followed by the eggs one at a time, mixing well after each addition. Stir in vanilla extract and sour cream.

Add Flour for Structure
Gradually add the flour, mixing just until combined. This helps the cheesecake hold together without becoming too dense.

Bake the Cheesecake
Pour the filling over the cooled crust in the springform pan. Bake for 55-65 minutes, or until the center is almost set but still slightly jiggly. Turn off the oven and let the cheesecake sit inside for 1 hour to prevent cracking.

Prepare the Topping
While the cheesecake is baking, mix crushed vanilla wafers, chopped pecans, and melted butter in a small bowl. Set aside.

Add the Crunchy Topping
After the cheesecake has cooled slightly, sprinkle the wafer-pecan mixture evenly over the top.

Chill Completely
Refrigerate the cheesecake for at least 4 hours, preferably overnight, before serving. This allows the flavors to meld and the cheesecake to firm up perfectly.