Preheat the oven to 170°C (340°F). Line your baking mold with parchment paper.

Cut 25 g unsalted butter into small pieces and melt it in a heat-safe bowl using a double boiler or in the microwave (15–30 seconds at a time), stirring until fully liquid. Set aside.

In a mixing bowl, crack in the 3 eggs and add 50 g granulated sugar.

Use an electric mixer (or hand whisk) to beat on low speed until the sugar dissolves. Increase to medium-high speed and whip until the mixture becomes pale, thick, and fluffy. You should see ribbons that briefly hold their shape when the batter falls.

Mix 60 g cake flour with 30 g cocoa powder, and sift into the egg mixture.

Fold gently with a spatula using an under-and-over motion. Mix until smooth with no visible dry flour, but don't overmix—this keeps your batter light.

Pour in the melted butter and fold until fully combined. The batter is now ready.

Pour the batter into the prepared mold, filling each mold about 70–80% full.

Bake in the middle rack at 170°C (340°F) for 20 minutes. The surface will puff up and form slight cracks—this is a good sign.

After 20 minutes, remove the brownies from the oven.

Place dark chocolate over the brownie.

Return to the oven, reduce the temperature to 100°C (212°F), and bake for an additional 5 minutes. Watch closely—just melt the chocolate, don't overbake.

Remove from the oven. Lift the brownies out using the parchment paper and carefully peel it off. Serve warm or let cool to room temperature.