1. Preheat oven to 400°F (200°C) and grease ramekins with butter, dusting with cocoa powder.

2. Melt dark chocolate and butter together in a heatproof bowl over simmering water, then let cool slightly.

3. Whisk eggs and sugar in a separate bowl until pale and frothy.

4. Fold in the sourdough starter until smooth and thick.

5. Pour melted chocolate into the starter mixture and stir gently to combine.

6. Sift flour, cocoa powder, and salt into the batter and fold until just incorporated.

7. Divide batter among prepared ramekins, filling each three-quarters full.

8. Bake for 10–12 minutes until edges are set but centers still wobble.

9. Let rest 1–2 minutes, then invert onto plates or serve directly in ramekins.

10. Dust with powdered sugar and serve with fresh berries or ice cream.