Step 1: Preheat oven to 325°F (163°C).
Step 2: In a medium bowl, mix graham cracker crumbs, 1/4 cup sugar, and 6 tablespoons melted butter until combined.
Step 3: Press mixture firmly into bottom of a 9-inch springform pan.
Step 4: Bake crust for 10 minutes, then remove and let cool.
Step 5: In a large bowl, beat cream cheese and 1 cup sugar until smooth.
Step 6: Add eggs one at a time, beating after each addition.
Step 7: Mix in mashed bananas, vanilla extract, and sour cream until well combined.
Step 8: Pour filling over cooled crust.
Step 9: Bake for 45-50 minutes until center is set but still slightly jiggly.
Step 10: Turn off oven, leave cheesecake in oven with door slightly open for 1 hour.
Step 11: Remove from oven and cool completely at room temperature.
Step 12: In a medium bowl, whisk pudding mix with cold milk until thickened.
Step 13: Spread pudding evenly over cooled cheesecake.
Step 14: In a small bowl, combine crushed vanilla wafers, pecans, brown sugar, and 2 tablespoons melted butter.
Step 15: Sprinkle crunch topping over pudding layer.
Step 16: Refrigerate cheesecake for at least 4 hours before serving.