Peppermint Frappé (1967)

Julian, a middle-aged single doctor, meets his childhood friend Pablo again. The latter is back from Africa and has just married a beautiful young blonde, Elena. Julian falls in love with her and tries to seduce her, but she mockingly pushes him away from her. He then finds that Ana, his nurse, bears a troubling resemblance to Elena. He decides to gradually transform Ana into Elena...