Steps
1. Preheat your oven to 180°C (350°F). Grease and line a small ramekin or cake tin.
2. Melt the dark chocolate and butter together in a heatproof bowl over simmering water, stirring until smooth.
3. Remove from heat, then stir in the sugar until well combined.
4. Beat the egg and vanilla extract together in a separate bowl.
5. Slowly add the egg mixture to the chocolate mixture, stirring continuously to avoid cooking the egg.
6. Add a pinch of salt and mix thoroughly.
7. Pour the batter into the prepared ramekin and bake for 12-15 minutes until the edges are set but the center remains slightly soft.
8. Let cool for 5 minutes, then invert onto a plate.
9. Dust with powdered sugar or cocoa powder if desired before serving.