Melt dark chocolate (200 g) and unsalted butter (100 g) together using the double-boiler method.
Stir until smooth and glossy, then set aside to cool slightly.
In a separate bowl, whisk together Karuppu Kavuni powder (50 g), cocoa powder (25 g), and wheat flour (15 g) until lump-free.
Beat 3 eggs until foamy.
Add powdered brown sugar in 3 batches, whisking continuously until the mixture becomes light brown and airy.
Add the dry mix to the egg-sugar mixture in 3 parts.
While adding the second batch, pour in the melted chocolate-butter mix and continue beating gently.
Add the final dry mix batch and whisk until smooth and light.
Line a baking tray with parchment paper and pour the batter evenly.
Add your favorite toppings on top.
Bake in a preheated oven at 180°C (356°F) for 25–30 minutes, or until a toothpick inserted in the center comes out slightly sticky.