01 - Preheat oven to 425°F. Generously butter four 6 oz ramekins and dust with cocoa powder, tapping out any excess.
02 - Combine chocolate and butter in a heatproof bowl set over simmering water, stirring until completely smooth. Remove from heat and allow to cool slightly.
03 - In a medium bowl, whisk together eggs, egg yolks, and sugar until the mixture becomes pale and thick.
04 - Fold the melted chocolate mixture into the egg mixture. Add flour and salt, gently mixing until just combined without overmixing.
05 - Divide batter evenly among the prepared ramekins and place them on a baking sheet.
06 - Bake for 11 to 13 minutes until the edges are set but the centers remain soft. Remove from oven and let rest for 1 minute.
07 - Combine raspberries, sugar, and lemon juice in a small saucepan over medium heat. Cook until raspberries break down and mixture simmers, approximately 4 minutes. Press through a fine mesh sieve to remove seeds. Add water to achieve desired consistency.
08 - Run a knife around the edges of each cake and invert onto serving plates. Spoon raspberry coulis around or over the cakes and serve immediately.