What is Ile flottante?

Ile flottante — Literally 'floating island', this is one of the great desserts of classic French cuisine. It's a very light meringue floating on a sea of custard sauce. The meringue is made from egg whites, sugar, vanilla extract and usually cream of tartar, and cooked in a bain-marie. There are lots of versions that stem from this classic, with various additions of caramel, jam, fruit or fruit purée.