In a medium bowl, combine graham cracker crumbs and melted butter. Mix until well combined. Press the mixture firmly into the bottom of a 9-inch springform pan to form the crust. Set aside.

In a large mixing bowl, beat the softened cream cheese with an electric mixer until smooth and creamy. Gradually add the powdered sugar and vanilla extract, mixing until fully incorporated.

Add the marshmallow fluff to the cream cheese mixture and beat until smooth and combined.

In a separate bowl, whip the heavy cream with lemon juice and a pinch of salt until stiff peaks form.

Gently fold the whipped cream into the cream cheese and marshmallow mixture until fully combined and smooth.

Pour the cheesecake filling over the prepared crust in the springform pan, spreading it evenly. Smooth the top with a spatula.

Cover the cheesecake with plastic wrap and refrigerate for at least 4 hours, or overnight for best results, until set.

Once set, remove the cheesecake from the springform pan and slice into wedges to serve.