Prepare the moulds by heavily coating the melted butter all over the insides.
Place the mould in the freezer.
Brush more melted butter over the chilled butter, then add a heaped teaspoon of cocoa powder into the mould.
Tip the mould so the powder completely coats the butter.
Tap any excess cocoa into the next mould and so on.
Place a bowl over a pan of barely simmering water, then slowly melt the chocolate and butter together.
Remove bowl from the heat and stir until smooth. Leave to cool for 10 minutes.
In a separate bowl whisk the eggs and yolks together with the sugar until thick and pale.
Use an electric whisk if preferred.
Sift the flour into the eggs, then beat together.
Pour the melted chocolate into the egg mixture in thirds, beating well between each addition, until all the chocolate is added and the mixture is thoroughly combined into a loose cake batter texture.
Tip the batter into a jug or bowl and either pour o ladle evenly divide between the moulds.
Chill for at least 20 minutes or 24 hours.
Preheat the oven to 180°C / 350°F / Gas mark 4.
Place the fondants on a baking tray, then cook for 10-12 minutes until the tops have formed a crust and they are starting to come away from the sides of their moulds.
Remove from the oven, then leave to sit for 1 minute before turning out.
Loosen the fondants by moving the tops gently so they come away from the sides.
Tip each fondant slightly onto your hand so you know it has come away, then tip back into the mould.
Serve with ice cream if using, on the side.