Preheat the oven to 220˚C/200˚C (fan).
To bake, start with 7 minutes for a thin outer shell with a completely molten interior, 8 minutes for a slightly thicker crust and a gooey heart. (Remember not all ovens are the same, you may need to cook slightly longer.)
To unmould, simply run the fine edge of a knife around between the top of the cake and the mould. It should then come out very easily.