Preheat oven to 220°C (425°F). Grease 4 ramekins with butter and dust with cocoa powder.
Melt chocolate and butter together in a heatproof bowl over simmering water (or microwave in 30-second bursts). Stir until smooth.
In a separate bowl, whisk eggs, yolks, and sugar until pale and thick.
Gently fold the melted chocolate mixture into the egg mixture.
Sift in the flour and salt. Mix gently until just combined.
Divide the batter evenly among the prepared ramekins.
Bake for 10–12 minutes until edges are set but centers remain soft.
Remove from oven, rest for 1 minute, then carefully invert onto dessert plates.
Serve immediately with vanilla ice cream or fresh berries.
