Preheat your oven to 400°F (200°C) and grease two 5-ounce ramekins with butter, then sprinkle a little sugar inside to prevent sticking.

In a microwave-safe bowl, combine the chopped dark chocolate and butter. Microwave in 30-second intervals, stirring in between, until everything is melted and smooth.

In a separate bowl, whisk together the whole egg, egg yolk, granulated sugar, vanilla extract, and salt until pale and slightly thick.

Gently fold the melted chocolate mixture into the egg mixture, ensuring they blend well. Sift in the flour and mix until just combined.

Pour the rich batter evenly into the prepared ramekins, about three-quarters full.

Place the ramekins on a baking tray and bake for about 11-12 minutes, until the edges are set and the center remains soft.

Let the cakes sit for 1 minute after baking. Carefully run a knife around the edges to loosen, then invert each ramekin onto a plate.

Dust the tops with powdered sugar and serve warm with fresh berries and ice cream.