I found this
Nutella Brownie recipe on Pinterest.
Most of the comments suggest that the original recipe is too simplistic and would not really turn out like the picture. However one of the comments by "Nliff" toward the bottom of the page offers a fix that does work. My attempt turned out perfectly the first time following their instructions.
You could also just add the Nutella cheesecake layer to a boxed brownie mix.
Fix/Revise posted by "Nliff": "I made these tonight! These turned out very addicting! After reading the comments I made a few changes. For the brownie layer I used two eggs
and two egg yolks. I also added a 1/2 cup of white sugar in addition to the brown sugar. I also used a heaping 1/2 cup of Nutella.
Mix all of the dry ingredients together first.
Cream the butter and Nutella together, then add the eggs one by one to that.
Finally, combine your wet & dry ingredients.
For the cream cheese layer, I used another heaping 1/2 cup of Nutella. I also creamed together the cream cheese and Nutella, then added the sugar and mixed until well combined.
Finally, I added the eggs one at a time. I stuck with the temp and time in the recipe. The result was a dense, fudgy brownie layer and smooth cream cheese layer… Just like the picture!"