Preheat oven to 325°F (160°C).
Mix graham cracker crumbs, melted butter, and sugar. Press firmly into a springform pan.
Beat cream cheese until smooth. Add sugar and blend until creamy.
Add mashed bananas, lemon juice, and vanilla. Mix until combined.
Add eggs one at a time, mixing slowly. Do not overmix.
Add heavy cream and mix until the batter is silky.
Pour batter over the crust.
Bake 55–65 minutes until edges are set and center is slightly jiggly.
Turn off oven, crack door, and let cool inside for 1 hour.
Remove and cool completely before refrigerating at least 4 hours.
Top with whipped cream and banana slices before serving.