01 - Preheat the oven to 350°F. Grease an 8-inch round springform pan and line the bottom with parchment paper.
02 - Combine chocolate and butter in a heatproof bowl set over simmering water. Stir continuously until smooth and remove from heat to cool slightly.
03 - Whisk the sugar and sea salt into the melted chocolate mixture until fully combined.
04 - Add eggs one at a time, whisking thoroughly after each addition. Stir in vanilla extract until the batter is glossy and thick.
05 - Pour the batter into the prepared pan and smooth the surface with a spatula. Bake for 25 to 30 minutes, until edges are set and center is slightly soft but not liquid. A toothpick should come out with moist crumbs.
06 - Allow the cake to cool completely in the pan on a wire rack. Once cooled, remove the cake from the pan and place on a serving plate.
07 - Top with fresh raspberries and dust with icing sugar if desired. Serve at room temperature.