Preheat and Prepare the Pan
Preheat your oven to 350°F (175°C). Line a 9x13-inch baking dish with parchment paper for easy removal.
Make the Brownie Batter
In a mixing bowl, whisk together the melted butter and sugar until smooth.
Add the eggs and vanilla extract, mixing until fully combined.
Sift in the cocoa powder, flour, and salt, and gently fold until the batter is smooth. Set aside.
Make the Cookie Dough
In another bowl, cream together the softened butter, brown sugar, and granulated sugar until light and fluffy.
Beat in the egg and vanilla extract.
Gradually add the flour, baking soda, and salt, mixing until just combined.
Fold in the chocolate chips.
Layer the Brookies
Spread the brownie batter evenly into the prepared baking dish.
Spoon the cookie dough on top in small dollops, then gently spread it to create an even layer.
Bake the Brookies
Bake in the preheated oven for 25–30 minutes, or until a toothpick inserted into the center comes out with moist crumbs.
Let cool in the pan for 15 minutes before transferring to a cooling rack. Allow to cool completely before slicing.
