Mix the egg, egg yolk, sugar and salt in a bowl with a hand mixer until the mixture turns lighter in colour. Melt the chocolate and butter in a thin-sided bowl over a gently boiling bain-marie stirring until smooth. Add to the egg mixture. Fold the flour into the mix and pour into the prepared cups. Place the cups on an oven tray
Approx. 18 mins. in the centre of an oven preheated to 180°C. Remove, dust with icing sugar, and serve immediately.