1
Preheat oven to 220 °C. Grease four ramekins and dust with cocoa powder.
2
Melt dark chocolate and butter together over a double boiler.
3
Whisk eggs, yolks, and sugar until thick and pale.
4
Fold the chocolate mixture into the egg mixture, then sift in flour and fold gently.
5
Pour into prepared ramekins and refrigerate for up to 24 hours.
6
Bake 10–12 minutes until edges are set but centre jiggles. Invert onto plates and serve immediately.