Begin by preheating your oven to 350°F (175°C). Line a 9x9-inch baking pan with parchment paper. Allow the parchment to hang over two sides of the pan for easy removal of the brookies after baking. If you don’t have parchment paper, you can use aluminum foil lightly greased with butter or non-stick spray. Proper preparation ensures your bars won’t stick and makes slicing simple.

Melt the Butter: Gently melt the butter in a microwave-safe bowl or over low heat on the stovetop. Let it cool slightly so it doesn’t scramble your eggs.

Mix the Sugars and Wet Ingredients: In a large mixing bowl, whisk together the melted butter, granulated sugar, and brown sugar until well combined. Add the eggs and vanilla extract, whisking vigorously until the mixture is smooth and shiny.

Dry Ingredients for Brownies: Sift the flour, cocoa powder, and salt into the bowl. Slowly fold the dry ingredients into the wet ingredients, mixing just until combined. Overmixing can lead to tough brownies, so stir gently and stop when you no longer see dry flour streaks.

Pour into Pan: Transfer the brownie batter into your prepared baking pan, using a spatula to level the top. Set aside while you prepare the cookie layer.

Cream Butter and Sugars: In a separate bowl, cream the softened butter, brown sugar, and granulated sugar until light and fluffy. This step usually takes about 2 minutes with an electric mixer, but can be done by hand with a sturdy whisk as well.

Add Egg and Vanilla: Beat in the egg and vanilla extract until fully incorporated. The mixture should be smooth and creamy.

Incorporate Dry Ingredients: In another bowl, whisk together the flour, baking soda, and salt. Slowly add this dry mixture to your wet mixture, mixing just until a soft cookie dough forms.

Add Chocolate Chips: Fold in the chocolate chips, ensuring they’re evenly distributed throughout the dough.

Gently drop small spoonfuls of the cookie dough over the brownie batter. It will be a bit sticky, so consider lightly wetting your hands or using two spoons to spread it out. Don’t worry if the layers aren’t perfectly even; the cookie dough will spread as it bakes.

Aim for a relatively even layer, but slight imperfections are part of the charm.

Place the pan in the preheated oven. Bake for 25-30 minutes, or until a toothpick inserted into the center comes out with just a few moist crumbs. The edges should look set, and the top cookie layer should be golden-brown.

Avoid overbaking. The brookies will continue to set as they cool. It’s better to have them slightly underdone for that soft, gooey texture rather than overly dry.

Allow the brookies to cool in the pan for at least 30 minutes. For cleaner slices, you can even refrigerate them for about an hour.

Lift the entire block out using the parchment paper overhang. Place on a cutting board and slice into squares. The size of each piece is up to you, but 16 squares (4x4) is a good starting point.