Method

1. Place a saucepan over a medium heat and fill ¾ full with water. Once the water is simmering, place a heat-proof bowl over the pan. Add the chocolate, turn the heat down to low and allow the chocolate to melt. Once melted, set aside to cool.
2. In a separate bowl, whisk the egg whites using an electric hand whisk until they form stiff peaks, this will take 4 to 5 minutes.
3. Add the sugar and continue to whisk until the mixture is stiff and glossy.
4. Next, add the yoghurt to the cooled chocolate. Beat to combine.
5. Using a large spoon, add a spoonful of the egg white mixture to the chocolate mixture and mix.
6. Gently fold the rest of the egg white mixture into the chocolate until combined. There should be no visible egg white.
7. Divide the mixture between 4 small ramekins/glasses and refrigerate for 2 hours.