Yes definitively the Prelude, which Ravel composed to the attention of then 14 yrs old Jeanne Leleu for her sight-reading examination for Paris Conservatoire graduation.
Otherwise there are also those two pieces "A la manière de... Borodine (Valse)" and "A la manière de... Chabrier" which are quite beautiful and do not sound too hard (but actually I don't know, maybe there's a trap).