01 - Preheat the oven to 425°F. Butter and lightly flour 4 ramekins, each about 6 oz.
02 - Combine chocolate and butter in a heatproof bowl set over barely simmering water. Stir until smooth, then remove from heat and allow to cool slightly.
03 - In a separate bowl, whisk the whole eggs, egg yolks, and granulated sugar until the mixture is thick and pale.
04 - Gradually add the melted chocolate mixture to the egg mixture and whisk until homogenous.
05 - Gently fold in sifted flour, vanilla extract, and salt until just incorporated; avoid overmixing.
06 - Distribute the batter evenly among the prepared ramekins.
07 - Place ramekins on a baking sheet and bake for 11 to 12 minutes until edges are set but centers remain soft.
08 - Allow cakes to cool for one minute, run a knife around edges, invert onto plates, dust with powdered sugar, and serve immediately with berries and ice cream if desired.