Preheat oven to 350 degrees F. Line a 9x13 inch pan with parchment paper. A 7x11 inch pan will also work well.

Melt butter in a saucepan over medium-high heat. The butter will begin to crackle and foam. Make sure you whisk consistently during this process. After a couple of minutes, the butter will begin to brown on the bottom of the saucepan; continue to whisk and remove from heat as soon as the butter begins to brown and give off a nutty aroma. Immediately transfer the butter to a bowl to prevent burning. Set aside to cool for 10 minutes. It is VERY important to let the butter cool so please do not skip this step.

With an electric mixer, mix the brown butter and sugar until thoroughly blended. Beat in the eggs and vanilla until well combined, smooth and creamy (about 1 min). 

Add the dry ingredients slowly and beat on low-speed just until combined. Gently fold in all of the chocolate chips.

Divide the cookie dough batter in half. Spread half of cookie dough onto prepared pan, patting towards the edges. Try to make sure that the batter is evenly distributed; it’s going to seem like a thin layer but they will bake up and be glorious.

Drop Nutella by tablespoonfuls on top of first layer of cookie dough. You’ll want to do this all around the pan, leaving a small amount of space on the edges. 

Next, spread Nutella with a spatula so that it’s in an even layer on top of the cookie dough. Top Nutella with remaining batter, making sure Nutella is completely covered. Tip: I drop a handful of cookie dough in different areas on top of the Nutella, then use my hands to pat the cookie dough into an even layer.

Bake for 23-27 minutes or until edges begin to turn a slight golden brown. I like to undertake mine a little so they stay gooey and soft in the middle. Allow to cool on a wire rack for 20 minutes before cutting into bars.