01 - Preheat oven to 425°F. Generously butter four 6 oz ramekins and lightly dust with flour, tapping out any excess.
02 - Set a heatproof bowl over a pot of gently simmering water. Add chocolate and butter, stirring until completely smooth and melted. Remove from heat and let cool for 2-3 minutes.
03 - In a separate bowl, whisk together the eggs, egg yolks, and powdered sugar until the mixture becomes pale and slightly thickened, about 1-2 minutes.
04 - Pour the warm chocolate mixture into the egg mixture along with vanilla extract. Whisk vigorously until fully incorporated and smooth.
05 - Sift the flour and salt over the batter. Gently fold with a spatula until just combined—do not overmix or the cakes may become tough.
06 - Divide the batter evenly among the prepared ramekins, filling each about three-quarters full.
07 - Place ramekins on a baking sheet 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. Run a thin knife around the edge of each ramekin, then invert onto plates. Wait 10 seconds before lifting off the ramekin. Dust with powdered sugar and serve immediately with berries and ice cream.