A crunchy, buttery graham cracker tart crust is filled with chocolate-y Nutella spread and topped with a marshmallow meringue. Toast the meringue until it's crisp and brown on the outside and meltingly gooey inside, for an elegant, no-bake take on the nostalgic s'more.
Place the remaining sugar, corn syrup, and water in a medium pot and bring to a boil over medium-high heat, swirling the pot occasionally.
Continue to cook until the syrup reaches about 240 degrees F (soft ball stage).
Slowly and carefully stream the hot syrup into the egg mixture, while stirring on low speed.
Once all the syrup has been incorporated, turn the mixer up to medium-high speed and whip until fluffy, thick, and white.
Stir in the vanilla extract and pipe or spoon the marshmallow meringue onto the tart.
Toast the meringue with a brulee torch (or under the broiler for a few minutes) until brown and slightly crisp.