1 Heat the oven to 200ºC (180º fan) 400ºF, gas 6. Grease a 20 cm x 30 cm/8" x 12" ovenproof dish.
2 Beat the eggs and egg yolks together with the sugar until the mixture is pale and fluffy then beat in the melted butter.
3 Fold in the flour, cocoa powder and chopped chocolate and pour into the dish.
4 Bake for 20-25 minutes or until the cake is firm to the touch. Let cool a little then dust with icing sugar and serve with whipped cream.