01 - Preheat oven to 425°F. Generously butter four 6 oz ramekins and dust with cocoa powder, tapping out excess.
02 - In a heatproof bowl, melt chocolate and butter together over a pan of simmering water, stirring until smooth. Remove from heat and cool slightly.
03 - In a medium bowl, whisk eggs, egg yolks, and sugar until pale and thick, about 2 minutes.
04 - Pour the melted chocolate mixture into the egg mixture; whisk gently to combine.
05 - Sift in flour and salt; fold together until just incorporated.
06 - Divide batter evenly among prepared ramekins. Place on a baking tray.
07 - Bake for 12 minutes, until edges are set but centers still look slightly soft. Remove from oven and let cool for 1 minute.
08 - While cakes bake, combine raspberries, sugar, lemon juice, and water in a small saucepan. Cook over medium heat, stirring occasionally, until raspberries break down and sauce thickens slightly, about 5–7 minutes. Strain through a fine sieve to remove seeds, if desired.
09 - Run a knife around cake edges, invert onto plates, and remove ramekins. Drizzle with raspberry sauce, dust with powdered sugar, and garnish with fresh raspberries and whipped cream or ice cream if desired.