A rich, fudgy brownie with a crisp top and extra chocolate pieces, perfect for a single generous serving.
Melt 400 g of dark chocolate together with the butter, stirring until smooth. Let the chocolate mixture cool. Meanwhile, chop the remaining 200 g of chocolate into small pieces.
Preheat the oven to 180 °C.
Whisk sugar, vanilla sugar and eggs together, then fold in the cooled chocolate mixture. Mix flour with salt and baking powder, and stir into the batter spoon‑by‑spoon, being careful not to overmix.
Line a deep baking tray with parchment paper and spread the batter evenly. Scatter the chopped chocolate on top (or fold it into the batter if you prefer). Bake on the middle rack for 25‑30 minutes until a light crust forms, keeping the brownies moist inside.