Graham Cracker Crust

Preheat oven to 350F. In a mixing bowl, combine the graham cracker crumbs, melted butter, and sugar. Press into the bottom and up the sides of a tart pan. Bake for 8-10 minutes or until the crust is lightly golden brown. Let cool completely. 

Filling

Add the Nutella® and softened cream cheese to a mixing bowl. Beat until smooth. Stir in the whipped topping. Spread into the bottom of the cooled graham cracker crust. Refrigerate for at least 2 hours. 

Marshmallow Topping

Combine the water, sugar, and corn syrup in a small saucepan. Place the pan over medium heat and bring it to a boil. Let the mixture boil until it reaches 220F. At that point, let it continue boiling while you get the egg whites going. Place the egg whites and cream of tartar to the bowl of a stand mixer fitted with the whisk attachment. Begin beating the egg whites until they reach soft peaks. When the sugar mixture reaches 240F, remove from the heat and slowly drizzle the hot syrup into the egg whites while the mixer is still running on medium-high speed. Once all of the syrup is incorporated, increase the speed to high and beat for 5 minutes or until stiff peaks form. Beat in the vanilla then spoon the mixture over the chilled tart. Use a kitchen torch to give the marshmallow a toasted look. Cut into slices and serve.