Preheat the oven to 325° F. Line a 13 x 18 sheet pan with parchment paper, letting it hang over both sides. (For thicker brookies, we recommend a 10x15" sheet pan - Adjust the baking time as needed.) Set aside.

Use a hand mixer to beat the melted butter and granulated sugar in a large bowl until smooth. Add the eggs and vanilla, whisking to combine. Then, stir in the oil and cocoa powder just until smooth.

Using a rubber spatula, stir in the flour, cornstarch, baking soda, and salt just until combined. Gently fold in the chocolate chips.

Pour the batter into the prepared sheet pan, smoothing it out evenly. Set aside.

Sift the flour, baking soda, and salt in a medium-sized bowl.

In a separate large bowl, mix the brown butter, brown sugar, and granultaed sugar until well combined. Add the eggs 1 at a time, beating for 1-2 minutes to combine. Then, add the vanilla extract, and beat for another 1-2 minutes or until smooth.

Slowly add the dry ingredients to the bowl of wet ingredients, mixing just until they’re combined. Be careful not to overmix!

Fold in the chocolate chips.

Crumble the cookie dough evenly over the brownie batter, covering it completely.

Bake 25-30 minutes for a 13x18 sheet pan or 30-35 minutes for a 10x15 sheet pan or just until the top is browned.

Remove from the oven, sprinkle the Maldon salt on top, and set aside to cool completely. Slice the brownies into bars, and serve!

Store in an airtight container at room temperature or in the fridge for up to 1 week.