Steps
1. Preheat your oven to 190°C (375°F) and butter a small ramekin.
2. Melt the dark chocolate in a microwave or double boiler until smooth.
3. In a separate bowl, whisk the egg yolk with the milk and sugar until combined.
4. Stir the melted chocolate into the egg yolk mixture until smooth.
5. In another bowl, whisk the egg white with a pinch of salt until stiff peaks form.
6. Gently fold the egg white into the chocolate mixture in three additions, being careful not to deflate the mixture.
7. Pour the mixture into the prepared ramekin and smooth the top.
8. Bake for 12-15 minutes until the soufflé has risen and the top is set but still soft inside.
9. Remove from the oven and dust with powdered sugar if desired before serving.