Line a 9 inch square baking pan with wax or parchment paper.

Pour and spread ⅔ cup Nutella into the prepared pan, creating an even layer. Place the pan in the freezer for an hour.

Preheat the oven to 350 degrees Fahrenheit.

Line a 9 inch square baking pan with parchment paper. Spray the parchment paper with nonstick cooking spray.

Over medium heat, melt the butter and chocolate chips in a medium-sized saucepan. Stir the mixture until it’s smooth, then remove from heat.

While the chocolate mixture is cooling, pull together the dry ingredients. In a medium- sized bowl, add the flour, cocoa powder, and salt. Whisk together. Set aside.

In a large bowl, combine the brown sugar, granulated sugar, eggs, and vanilla. Whisk until fully combined and smooth. Add in the chocolate mixture and whisk again until smooth.

Fold the dry ingredients in with the wet ingredients. Use a rubber spatula or wooden spoon and mix until everything is fully combined.

Fold in the chocolate chips.

Pour the brownie batter into the bottom of the prepared pan, creating an even layer. Place the pan into the oven and bake for 15 minutes.

Prepare the cookie dough while the brownie layer is in the oven. Combine the room temperature butter, brown sugar, and granulated sugar in a stand mixer (or using a handheld mixer) on medium speed. Beat for about 2-3 minutes or until the mixture is light and fluffy.

Add the egg and vanilla and beat until combined.

Gradually add in the dry ingredients on low speed until just combined.

Fold in the chocolate chips with a rubber spatula.

After 15 minutes, remove the brownies from the oven and remove the Nutella layer from the wax/parchment paper and gently place it on top of the brownie layer.

Break the cookie dough into smaller pieces, creating an even layer on top of the Nutella. If the cookie dough doesn’t cover all of the Nutella, that’s okay – the cookie dough will spread while it’s baking.

Place the pan into the oven and bake for about 25-30 minutes. The brookies are done when the cookie layer is set and light golden in color. You can also use the toothpick test to see if they're done. If you insert a toothpick into the pan, you should be left with moist crumbs once removed. Once removed from the oven, top with flaky sea salt.

Let the brookies cool and set before slicing. I’d recommend waiting at least 2 hours or letting them set overnight (this is what I do). When slicing, be sure to wipe the blade clean between each slice as the Nutella will be at room temperature and gooey.

Use a knife to slice the bars into 12 (larger) or 16 (smaller) pieces.

Store in an airtight container at room temperature for 1 week or freeze for up to 3 months.