01 - Preheat oven to 425°F. Generously butter four 6 oz ramekins and dust with cocoa powder, tapping out excess.
02 - Melt chocolate and butter together in a heatproof bowl set over a saucepan of barely simmering water, stirring until smooth. Remove from heat and let cool slightly.
03 - In a separate bowl, whisk eggs, egg yolks, and sugar until thick and pale, about 2–3 minutes.
04 - Fold the melted chocolate mixture into the egg mixture. Add flour and salt, folding gently until just combined.
05 - Divide batter evenly among prepared ramekins. Place ramekins on a baking sheet.
06 - Bake for 10–12 minutes, until edges are set but centers are still soft. Do not overbake.
07 - Let cakes rest for 1 minute, then run a knife around the edges and invert onto serving plates.
08 - Serve immediately with a generous scoop of vanilla bean ice cream.