1-First, preheat the oven to 325°F (163°C) and line the bottom of a 9-inch springform pan with parchment paper. Crush the vanilla wafers finely using a food processor or blender, then mix the crumbs with granulated sugar and melted unsalted butter until moist. Press this mixture firmly into the bottom of the springform pan and bake for 10 minutes, then set it aside to cool.

2-Next, boil a large pot of water for the water bath, which is crucial for even cooking. In a mixer, beat the softened cream cheese until smooth, then add the mashed ripe banana and sour cream, mixing until combined. Incorporate the granulated sugar, dry instant banana pudding mix, and pure vanilla extract, ensuring everything blends well without adding liquid to the pudding mix.

3-Adding Eggs and Baking: Lightly beat the 4 large eggs separately, then fold them into the filling gently to avoid overmixing, which keeps the texture creamy. Wrap the springform pan in 2 to 3 layers of foil and place it inside an oven-safe bag with sides folded down to prevent water seepage. Pour the cheesecake filling into the cooled crust and smooth the top, then place the pan into a roasting pan with about one inch of boiling water.

4-Bake for 70 to 80 minutes, or until the edges are set but the center is slightly jiggly. Turn off the oven, crack the door slightly, and let the cheesecake cool inside for 1 hour to prevent sudden temperature changes. Remove it from the oven, cool completely on a wire rack, and refrigerate for 5 to 6 hours or overnight before serving. For neat slices, dip a sharp knife in hot water and dry it before cutting, as suggested in the tips.