In a food processor or blender, crush graham crackers. Add melted butter and granulated sugar, pulsing until fully combined and fragrant.
Press the crust mixture into the bottom and up the sides of a 9-inch springform pan, ensuring even distribution. Chill for 10 minutes to set.
Beat softened cream cheese on medium speed until smooth. Gradually add sifted powdered sugar and vanilla extract, mixing until light and airy.
Whip cold heavy cream in a separate bowl until stiff peaks form. Gently fold the whipped cream into the cream cheese mixture.
In a 9-inch round pan, spread half the filling over the crust. Layer banana slices evenly, then add the remaining filling, smoothing the top.
Spread marshmallow fluff over the filling, slightly pressing bananas into the fluffy layer. Chill for 4–6 hours until firm.
Remove from pan, slice into 12 wedges, and serve chilled.