01 - Preheat the oven to 425°F. Generously grease four 6 oz ramekins with butter and dust with cocoa powder, tapping out any excess.
02 - Set a heatproof bowl over a pot of simmering water to create a double boiler. Add the chopped chocolate and butter, stirring until completely melted and smooth. Remove from heat and let cool slightly.
03 - In a separate mixing bowl, whisk together the granulated sugar, whole eggs, and egg yolks until the mixture becomes thick and pale in color.
04 - Gradually stir the melted chocolate mixture into the egg mixture. Add the vanilla extract and salt, mixing until fully incorporated.
05 - Sift the flour into the batter and gently fold it in until just combined. Be careful not to overmix, which can affect the texture.
06 - Divide the batter evenly among the prepared ramekins. Place the ramekins on a baking sheet for easy handling.
07 - Bake for 11 to 12 minutes. The edges should be set while the centers remain soft and slightly jiggly. Avoid overbaking to preserve the molten center.
08 - While the cakes bake, combine raspberries, sugar, lemon juice, and water in a small saucepan over medium heat. Cook for 5 minutes, stirring occasionally, until the raspberries completely break down.
09 - Pour the raspberry mixture through a fine mesh sieve into a clean bowl, pressing with a spoon to extract as much liquid as possible while removing the seeds. Set aside to cool.
10 - Remove the cakes from the oven and let them rest for 1 minute. Run a knife around the edges of each ramekin, then carefully invert onto serving plates. Dust with powdered sugar, drizzle with raspberry coulis, and garnish with fresh raspberries and mint leaves if desired. Serve immediately.