Preheat your oven to 350°F (175°C). Line an 8×8-inch baking pan with parchment paper or lightly grease it. This makes removing the brookies much easier once they are baked.

In a mixing bowl, whisk together the melted butter and granulated sugar until smooth. Add the eggs and vanilla extract, then mix until fully combined. Stir in the cocoa powder, flour, and salt until a thick, smooth batter forms.

Pour the brownie batter into the prepared baking pan and spread it evenly with a spatula so it covers the entire bottom of the pan.

In another bowl, beat the softened butter with the granulated sugar and brown sugar until creamy. Add the egg and vanilla extract and mix well. Stir in the flour, baking soda, and salt until a soft dough forms. Fold in the chocolate chips.

Drop spoonfuls of the cookie dough over the brownie batter. Gently spread or flatten the dough so it covers most of the brownie layer. It doesn’t need to be perfect; small gaps will fill in during baking.

Place the pan in the preheated oven and bake for about 25–30 minutes. The cookie layer should turn golden brown while the brownie layer remains slightly fudgy.

Allow the brookies to cool completely in the pan before slicing. This helps the layers set properly and makes cutting clean squares much easier.