Now that's interesting. To me, flan is something entirely different from quiche (though not, of course, resembling creme caramel either.) Basically it is a pudding consisting of a very particularly shaped shallow base-plus-edge made of spongy stuff, filled with your choice of fruit(s) in jelly. That's the best description I can come up with, anyway. It was a regular pudding in my childhood, especially but not only at grandparents' houses. I believe one can/could buy ready-made flan-cases from shops. I must admit I haven't had a flan in years and years, and it is probable that I never had a quiche until after I had my last flan, but as quiche is savoury they nonetheless occupy entirely different places in my mind.