Kourtney Kardashian 40 Going on 20!!! Famous Friends Get Down

4/19/2019 7:24 AM PDT

Kourtney Kardashian Turned 40 and Celebs Joined the Celebration

If Kourtney Kardashian turned 40 you wouldn't know it based on her never-aging looks ... but the big giveaway was her HUGE birthday bash populated by her famous friends.

Kourtney celebrated the big 4-0 Thursday night in L.A. in one of the most epic celebrations ever, or at least this month. Kim, KhloeKris JennerKylie and Kendall were all there ... as was Kanye and TONS of other celebs ... including French Montana, Paris Hilton and Larsa Pippen. Even her ex, Younes Bendjima, was partying it up.

A bunch of Kourtney's friends also shared some of their best memories of her:

No expense was spared for the swanky shindig ... the Don Julio 1942 bottles were flowing as were the inside jokes inscribed on napkins. If you're a huge fan of "Keeping up with the Kardashians," you know what's up. But, here's what takes the cake ... the damn cake itself!!! It's a massive desert showing off Kourtney's very own cakes.

Robin Thicke and Sia sang Kourtney "Happy Birthday" and a great time was had by all.

Keep aging like fine wine, Kourtney.