Check out these pics -- the 78-year-old legend's absolutely smitten during her steamy make-out session with Alexander at the amfAR Gala at the Hôtel du Cap-Eden-Roc Thursday -- and with their 40-year-age gap, they're proving age is truly nothing but a number.

Cher's rocking a glamorous furry coat while Edwards is looking sharp in a matching black suit -- and with their impeccable style, it's no wonder they couldn't take their eyes off each other.

In those rare moments when they manage to tear themselves away from each other's lips, they're giggling like a couple of school kids.

After all, Cher said it herself recently ... she prefers dating younger guys 'cause they're not intimidated by her.

Believe it or not, Cher admitted she's actually pretty shy when she's not up on stage rocking it out. With that in mind, she prefers guys to make the first move.

But apparently, fellas her age just haven't been stepping up to the plate and have been a tad too intimidated to shoot their shot.

She said in contrast, the younger crowd like Alexander are all about seizing the moment ... something for which she's grateful!