01 - Preheat oven to 425°F. Generously butter four 6 oz ramekins and lightly dust with flour, tapping out the excess.
02 - Set a heatproof bowl over a pot of gently simmering water. Melt the chocolate and butter together, stirring until smooth and glossy. Remove from heat and let cool slightly.
03 - In a separate bowl, whisk together the eggs, egg yolks, and powdered sugar until pale in color and slightly thickened, about 2 minutes.
04 - Pour the melted chocolate mixture and vanilla extract into the egg mixture. Whisk vigorously until fully combined and smooth.
05 - Sift the flour and salt directly into the batter. Using a rubber spatula, gently fold until just incorporated. Be careful not to overmix.
06 - Evenly divide the batter among the four prepared ramekins, filling each about three-quarters full.
07 - Place ramekins on a baking tray and bake for 11–12 minutes. The edges should be set while the centers remain soft and slightly jiggly when gently shaken.
08 - Let cakes rest for 1 minute. Carefully run a knife around the edge of each cake, invert onto plates, and wait 10 seconds before lifting off the ramekin. Dust with powdered sugar and serve immediately with berries and ice cream.