This is the easiest, squidgiest, most delicious chocolate cake ever ! I had this for my birthday cake but it would also be a wonderful dessert for a dinner party with a blob of creme fraiche. If baked for 25 minutes as suggested, the centre is quite fondant, ie. very soft. If you want it more cakey, just cook for another 5 minutes or so. It doesn't really need icing, but I've added a footnote with a suggested frosting recipe.
Frosting: Melt 60g of dark chocolate. Add 2 tablespoons fresh cream. Add enough icing sugar to make it thick enough to ice with. Spoon over cake and let dribble down sides.