01 - Preheat oven to 425°F. Butter four 6 oz ramekins and dust with cocoa powder, tapping out excess.
02 - Melt dark chocolate and butter together in a heatproof bowl over simmering water, stirring until smooth. Remove from heat and cool slightly.
03 - In a separate bowl, whisk eggs, egg yolks, and granulated sugar until pale and slightly thickened.
04 - Gently fold the melted chocolate mixture into the egg mixture until combined.
05 - Sift flour and salt into the mixture and fold until just incorporated, avoiding overmixing.
06 - Divide batter evenly among 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 - Remove from oven and let stand 1 minute. Run a knife around edges and invert each cake onto dessert plates.
09 - Serve immediately with a scoop of vanilla ice cream. Optionally dust with powdered sugar and garnish with berries or mint.