01 -
Turn your oven to 325°F. Line a 9-inch square pan with parchment, making sure the paper hangs over the edges. Spray with nonstick spray.
02 -
In a medium-sized pan on low heat, stir together the butter, chopped chocolate, and 1 cup of the chocolate chips. Keep mixing until it’s smooth and shiny. Let it cool a little afterward.
03 -
In a big bowl, whisk eggs, Nutella, sugar, and vanilla well. Combine this with the slightly cooled chocolate mixture until it’s blended.
04 -
Sift the flour, salt, and baking powder together. Slowly mix it into the wet batter. Add the last of the chocolate chips and 1 cup of the hazelnuts, stirring gently.
05 -
Pour everything into the pan you prepped earlier. Scatter the rest of the hazelnuts on top. Bake for 40 minutes. Cover the pan with foil and bake another 10–15 minutes until the center is mostly set. Let it cool fully before cutting.