Updated: Inside Rihanna's Star-Studded 23rd Birthday Bash

Ri Ri turned 23 in style over the weekend and we have the details.  Rihanna rocked out with some of music's biggest names – but also found time for some quiet celebrating with old friends.

Rihanna partied a private home in Beverly Hills after performing at the NBA All-Star Game in Los Angeles. When she arrived, a party guest tells PEOPLE that she was treated to a taste of home – in the form of Sprinkles red velvet cupcakes with the Barbados flag imprinted on them.

She grabbed a full-sized confection, announcing, "I'm so hungry," the source says.

Before all her guests arrived, Rihanna managed to sneak away to party with her best girlfriends in a secluded room in the Beverly Hills house. When she later joined the main party, she sported a tight-fitting pink dress with some purple fringe around the skirt.

There, she greeted her high-wattage friends warmly. "She [gave] Ryan Phillippe and Zac Efron huge hugs," the source says, adding that the two actors hung out together and chatted throughout the night.

Also on hand: Cee Lo Green and his crew, who were spotted noshing on some of Oxtail and plantains, as well as Mary J. Blige and Jay-Z, who were "laughing and having a blast posing for photos in corner of the party," the source says. Blige also "squealed with excitement" when she caught sight of Diddy, and they shared a long hug.

Later, Snoop Dog and Warren G rolled in at 1 a.m. and proceeded to danceJJoel Madden and Christina Milian were also celebrating with the birthday gal, and both them indulged in vanilla and red velvet cupcakes, respectively.