Melt the chocolate and the butter in a double boiler. Alternatively place the chocolate and butter in to a glass mixing bowl and place on top of a saucepan filled with a little water, gently bring the water to the boil and then simmer to melt the chocolate and butter.
Mix the sugar, the flour and the eggs in a salad bowl.
Add the melted chocolate/butter mixture, and then mix well.
Pour the mixture into the ramekin moulds which you should have buttered beforehand (flour should be sprinkled onto these before pouring in the mixture, to make it easy to remove the moulds afterwards).
Cook for between 10 and 15 minutes. The fondant should be cooked on the top and very creamy inside.
Remove from the mould right away, and serve with a scoop of ice cream.