Drop the Nutella mixture by heaping spoonful over the blondie mixture. Using a knife, swirl the Nutella batter over the blondie batter until it is evenly distributed.
Transfer to 350F oven (175C) and bake for 30 minutes or until toothpick inserted in the center comes out mostly clean with only a few crumbs.
Allow blondies to cool completely in pan before slicing and serving.
Video
Notes
*If your cream cheese is still cold and difficult to stir, I find it helpful to pop it in the microwave in a microwave safe bowl and heat at ten second increments until it is easily stirred with a spoon.