Cameron Diaz celebrated her birthday with a private cooking class.

The group, who dressed casually but had their garments protected by aprons, enjoyed a trattoria-themed class where they learned to produce Italian delights including wild mushroom risotto, salad and tiramisu.

And at the end of the class, Cameron was presented with a yellow birthday cake topped with chocolate frosting and candles as everyone sang 'Happy Birthday' to her.

A source told Us Weekly magazine: "It was great energy, super-positive, laughing, just celebrating a birthday.

"People did bring gifts, but [Cameron] didn't open them. It was a really lovely birthday dinner party, just really good vibes. Nothing out of the ordinary. They stayed for around three hours."

According to the onlooker, the group were having a great time at the class and were seen enjoying "toasts and cheers and hugs and kisses."

Both Benji, 37, and Gwyneth, 43, took to social media to praise the birthday girl.

The Good Charlotte rocker spoke of how "lucky" he feels to be married to the actress.

He wrote "Happy Birthday to my beautiful Wife. You're my best friend and I'm so thankful for you, sometimes I just want to tell the world. Generous, Kind, Compassionate, Selfless, Humble, Thoughtful, Patient and Loyal. Just a few of the qualities I would use to describe who you are, consistently, everyday. Thank you for being you, I'm a lucky guy. Here's to many more. Love you."

Meanwhile, Gwyneth admitted she is thankful to be friends with the blonde beauty.

She shared a picture of Cameron and her pal Drew Barrymore and wrote: "Dear @camerondiaz, before the day ends, I bid you a happy birthday, and I hit the ground with gratitude for getting to be one of the women who calls you a best friend."