Lunga vita alla signora (Long Live the Lady!) (1987)

The Lady (or Signora) of the title is a mysterious matron who lives in a crumbling mansion. Six catering trainees are brought to the castle upon its conversion into a resort hotel. They are ordered to prepare a special meal for the old lady, whom none of them have ever seen for more than an instant. As the caterers grow in wisdom and sophistication, we learn that the lady may very well be an urbane ghost rather than a flesh-and-blood entity.