Preheat the oven to 180°C Butter and flour six 140ml ramekins. (I used used cocoa instead of flour, it gave a stronger cocoa flavour.) Place the chocolate and butter in a heatproof bowl over a saucepan of simmering water. Make sure the bowl doesn’t touch the water. Melt until thick and glossy.
Whisk the caster sugar, eggs and egg yolks together until the mixture reaches ribbon stage – it should be thick, creamy and holding its shape. Pour the melted chocolate over the egg mixture, and sift on the flour. Use a large metal spoon to carefully fold the flour into the mixture. Divide the mixture between the prepared ramekins, leaving space at the top for the fondants to rise.
Place the remaining ramekins in the oven and bake for 9-10 minutes. Be careful of the temperature and cooking time -- when cooked, the fondant should be molten and oozy in the centre. Youc could test by cooking 1 fondant first if you prefer.
Remove from the oven and allow to rest for a minute or two. If the ramekins are too hot to handle, use a tea towel to turn them out on to plates. Dust the fondants with cocoa or icing sugar and serve with cream.