Hetty, that bloom sure looks like Epiphyllum oxypetalum which has flat leaves:
Queen of the Night (Epiphyllum oxypetalum)
Edited to add: I have a very sensitive sense of smell but it's weird because I can't seem to detect much fragrance on them and yet my husband and everyone else say the flowers are Extremely Fragrant! I've found the same with the Evening Glory flower (Ipomoea alba) ... everyone says they smell so good and I can't smell anything.
