Lightly grease cupcake tins or ramekins then dust with cocoa.
Beat eggs and sugar together.
Add the melted dark chocolate, the butter and then the flour.
Spoon the batter into the prepared tin or ramekins and bake for 11 minutes, or until the sides of the cakes are firm but the centres are soft.
Note: since all ovens are different, we recommend you to bake just one cake first to figure out the right amount of time it takes to get a perfectly soft and gooey centres. It could take between 10 and 13 minutes.