Preheat the oven to 180°C (356°F).
Mix the brownie batter ingredients (dark chocolate, butter, sugar, eggs, cake flour, salt) thoroughly.
In another bowl, mix the cookie dough ingredients (butter, sugar, eggs, cake flour, baking soda, chocolate chips, salt).
Pour the brownie batter into a baking pan and spread the cookie dough on top.
Bake in the preheated oven for 25–30 minutes and let cool.