01 -
Heat oven to 325°F. Coat a 9-inch square pan with cooking spray. Line it with parchment and leave a couple of inches dangling over all four edges.
02 -
On medium-low heat, use a medium-sized pan to melt butter, chopped chocolate, and 1 cup of chocolate chips together. Stir occasionally until smooth, then cool slightly.
03 -
In a big bowl, whisk the eggs, Nutella, sugar, and vanilla. Blend this into the slightly warm chocolate mix.
04 -
Sift the flour, salt, and baking powder into a bowl. Mix them into the chocolate blend. Gently stir in the leftover chocolate chips and 1 cup of hazelnuts.
05 -
Pour the batter into the lined pan. Add the rest of the toasted hazelnuts on top. Bake for 40 minutes, then loosely cover with foil and bake another 10-15 minutes until slightly firm. Let it cool all the way before slicing.