01 - Preheat oven to 425°F. Generously butter four 6 oz ramekins and lightly dust with flour, tapping out the excess.
02 - In a heatproof bowl set over a pot of gently simmering water, melt the chocolate and butter together, stirring until smooth. Remove from heat and let cool slightly.
03 - In a separate bowl, whisk together the eggs, egg yolks, and powdered sugar until pale and slightly thickened.
04 - Add the melted chocolate mixture and vanilla extract to the egg mixture, whisking until fully combined.
05 - Sift in the flour and salt, and gently fold until just incorporated. Do not overmix.
06 - Evenly divide the batter among the prepared ramekins.
07 - Place ramekins on a baking tray and bake for 11-12 minutes, until the edges are set but the centers are still soft and slightly jiggly.
08 - Let rest for 1 minute, then carefully run a knife around the edge of each cake. Invert onto plates and let stand for 10 seconds before lifting off the ramekin. Dust with powdered sugar and serve immediately with berries and ice cream.