Preheat oven to 325°F (160°C). Mix graham cracker crumbs, melted butter, sugar, and salt. Press mixture into a parchment-lined 9x13 inch baking pan. Bake for 8–10 minutes.
In a large bowl, beat softened cream cheese until smooth. Add powdered sugar and beat again until fluffy.
Mix in Nutella, eggs, vanilla extract, heavy cream, and flour until fully incorporated and smooth.
Pour the filling over the baked crust. Spoon extra warm Nutella on top and swirl with a knife for a marbled effect.
Bake for 25–30 minutes, or until the center is set but still slightly jiggly. Remove and let cool to room temperature.