I finally made this cupcake yesterday. It was really yummy. I should have mixed the nutella with the base but i add a drop on top of the cake before baking. But it still ended tasting good.
The recipe of this muffin is already been posted in this blog. The base is the same. First place the base alogn with a blob of the nutella. Then add the blueberries to the base and make a blueberry muffin. I am posting a picture below.