Ingredients :

• Dark chocolate — This is the heart of the recipe. Between 60 and 70% cocoa—any lower and the batter will be too sweet and lose that bitterness that balances everything. A Lindt 70% or any 70% dark bar from the supermarket works perfectly. Avoid low-end cooking chocolate: it often tastes like plastic once melted.
• Butter — It melts with the chocolate and gives that fatty, melting texture impossible to get otherwise. No margarine, no vegetable oil. Unsalted or semi-salted, both work—with semi-salted, you get that small salt-chocolate contrast that makes a difference in the final bites.
• Eggs — Three whole eggs, whisked with the sugar before incorporating the chocolate. This whisking creates a light foam that aerates the batter slightly. Without it, the texture would be too compact, almost heavy. Take them out of the fridge 20 minutes before—they incorporate better at room temperature.
• Flour — Only 80g, and that’s intentional. The low amount of flour is exactly what differentiates a brownie from an ordinary chocolate cake. If you are gluten-free, cornstarch works as a direct replacement, gram for gram.