01 - Preheat the oven to 425°F. Grease four 6-ounce ramekins with butter and lightly dust with flour or cocoa powder, then tap out the excess.
02 - Melt the chopped chocolate and butter together either over a double boiler or in short microwave bursts, stirring until smooth. Allow the mixture to cool slightly.
03 - In a medium bowl, whisk the eggs, egg yolks, and sugar until pale and thick, about two minutes.
04 - Gently fold the melted chocolate mixture into the egg mixture until just combined.
05 - Sift in the flour and salt, folding gently until the batter is smooth and uniform.
06 - Divide the batter evenly among prepared ramekins placed on a baking tray. Bake for 11 to 12 minutes until edges are set and centers remain soft. Avoid overbaking.
07 - While baking, combine raspberries, sugar, and lemon juice in a small saucepan. Cook over medium heat for 3-4 minutes until berries break down. If a thicker coulis is desired, stir in cornstarch dissolved in 1 teaspoon water and cook for one additional minute. Remove from heat, strain to remove seeds, and let cool.
08 - Allow cakes to rest for one minute after baking. Run a knife around the edges then invert each cake onto serving plates.
09 - Dust with icing sugar and serve immediately with the raspberry coulis and fresh raspberries if preferred.