Ingredients:
- 1 box of chocolate cake mix (plus ingredients listed on the box)
- 1 cup of Nutella
- 1/2 cup of heavy cream
- 1/4 cup of chopped hazelnuts (optional)

Instructions:
- Preheat your oven to 350°F (175°C) and grease a 9-inch square baking dish.
- Prepare the chocolate cake mix according to the instructions on the box.
- Pour half of the batter into the prepared baking dish.
- In a small bowl, mix together the Nutella and heavy cream until smooth.
- Pour the Nutella mixture over the batter in the baking dish, spreading it out evenly.
- Pour the remaining batter over the Nutella mixture, spreading it out to cover.
- Bake the cake for 25-30 minutes, or until a toothpick inserted into the center comes out clean.
- Let the cake cool for a few minutes before slicing and serving.
- Sprinkle chopped hazelnuts over the top of the cake, if desired.
Enjoy your delicious Nutella box cake!