Sift the all-purpose flour, cocoa powder, salt and baking powder into a medium sized bowl and set aside.
In a seperate small bowl cream the granulated sugar, 4 tablespoons of softened butter together. Add the eggs and vanilla extract to the bowl beating one egg in at a time.
Fold the flour mixture into the bowl ingredients and mix with a wooden spoon or spatula until combined.
Spread ¾ of the Nutella brownie batter into the bottom of the 8 x 8 baking pan with a small metal spatula. Spread the thick brownie batter into all 4 corners of the baking pan.
Next spread the filling batter over the brownie batter in the baking pan leaving a one inch border of brownie batter uncovered around the edges of the pan.
Randomly dollop the remaining brownie batter and the remaining ¼ cup of Nutella over the top of the pan. Use the tip of a knife to swirl the brownie batter and Nutella into the filling layer.
Bake the Nutella brownies in a preheated oven for 40 minutes for gooey fudgy Nutella brownies. For cake likeNutella brownies bake for 50 minutes.
Cool completely before cutting.