Begin by preheating your oven to 180°C (350°F) and lining an 8×8-inch square baking dish with parchment paper.
In a mixing bowl, combine the melted butter and granulated sugar, stirring until thoroughly blended.
Add the eggs and vanilla extract into the butter-sugar mixture, ensuring a smooth and creamy batter.
In a separate bowl, sift together the flour, cocoa powder, baking powder, and salt. Gradually add this dry mixture to the wet ingredients, stirring until a thick brownie batter forms.
Evenly spread the brownie batter into the prepared baking dish.
Arrange the Oreo cookies on top of the brownie batter in a single layer.
Now, let’s prepare the chocolate chip cookie layer.
In another bowl, cream together the softened butter, light brown sugar, and granulated sugar until the mixture becomes light and fluffy.
Add the egg and vanilla extract to the butter-sugar mixture, mixing well.
Sift together the flour and baking soda in yet another bowl. Gradually incorporate this dry mixture into the cookie dough, ensuring thorough mixing.
Gently fold in the chocolate chips.
Spoon dollops of the chocolate chip cookie dough over the brownie layer and Oreo cookies, spreading them out evenly.
Bake in the preheated oven for 25-30 minutes, or until the Brookies are firm but still slightly gooey in the centre.
Allow the Oreo Brookies to cool in the baking dish for approximately 15 minutes, then transfer them to a wire rack to cool completely.
Once cooled, cut the Brookies into squares and savour your delightful Oreo Brookies!