01 - Preheat oven to 425°F. Generously butter 4 individual ramekins (6 oz each) and lightly dust with cocoa powder; tap out the excess.
02 - Melt the chocolate and butter together in a heatproof bowl set over barely simmering water, stirring until smooth. Remove from heat and let cool slightly.
03 - In a separate bowl, whisk together eggs, egg yolks, powdered sugar, vanilla, and salt until thick and pale.
04 - Gently fold the melted chocolate mixture into the egg mixture until just combined.
05 - Sift in the flour and fold gently, taking care not to overmix.
06 - Divide the batter evenly among the prepared ramekins. Place ramekins on a baking sheet.
07 - Bake for 11–12 minutes, until the edges are set but the centers are still soft. Do not overbake.
08 - While cakes bake, combine raspberries, sugar, lemon juice, and water (if using fresh berries) in a small saucepan. Simmer over medium heat for 4–5 minutes until berries have broken down. Press through a fine mesh sieve to remove seeds. Set aside to cool.
09 - Let cakes rest for 1 minute, then run a thin knife around the edges and invert onto serving plates.
10 - Spoon raspberry sauce around or over the cakes. Garnish with fresh raspberries and a dusting of powdered sugar. Serve immediately, optionally with vanilla ice cream or whipped cream.