01 - Preheat oven to 425°F. Butter and lightly flour 4 ramekins (6 oz size), tapping out the excess flour.
02 - In a heatproof bowl set over a pot of simmering water, melt the chocolate and butter together, stirring until smooth. Remove from heat and let cool slightly.
03 - In a separate bowl, whisk together eggs, egg yolks, and sugar until thick and pale, about 2 minutes.
04 - Gently fold the melted chocolate mixture into the egg mixture. Stir in vanilla and salt.
05 - Sift flour over the batter and fold gently until just combined.
06 - Divide the batter evenly among the prepared ramekins.
07 - Place ramekins on a baking sheet and bake for 11–13 minutes, until the edges are set but centers are still soft.
08 - While the cakes bake, prepare the raspberry sauce: In a small saucepan, combine raspberries, sugar, lemon juice, and water. Cook over medium heat for 4–5 minutes, stirring and mashing berries until thickened. Strain through a fine mesh sieve to remove seeds, if desired.
09 - Let cakes cool for 1 minute, then run a knife around the edges and invert each cake onto a serving plate.
10 - Spoon raspberry sauce over each cake. Dust with powdered sugar and garnish with fresh raspberries. Serve immediately, ideally with ice cream or whipped cream.