Preheat your oven to 425°F (220°C). Grease four ramekins with butter and dust with flour.

In a microwave-safe bowl, melt the dark chocolate and butter together in short bursts until smooth.

In another bowl, whisk together eggs, egg yolks, and sugar until light and fluffy. Stir in the melted chocolate mixture and vanilla extract.

Gently fold in flour until just combined; avoid overmixing.

Divide the batter among the ramekins and bake for 12-14 minutes until edges are firm but centers are soft.

Let cool for one minute, run a knife around edges, invert onto plates, and serve warm.