Charlize Theron‘s son, Jackson, turns one this month! Hooray!

Seems like only yesterday the Snow White and the Huntsman actress, 37, announced that she was going to adopt a kid. Now, a year later, she’s partying it up with her little baby boy. On Jan. 8, Theron hosted a superhero-themed soiree for her little boy at the Coop, a play space for kids in L.A.’s Studio City. (Ashlee Simpson and ex-husband Pete Wentz threw a similar style party at the same venue for son Bronx’s 4th birthday in November.) The event featured big lollipops and jelly rings, cupcakes topped with Spiderman’s face, and special appearances by Wonder Woman and Batman.

And the best part of a kids party: champagne for the parents!

“It was a really mellow party,” a source tells Us Weekly of the celebration, which was attended BY a few of the actress’ famous friends, including Marley Shelton and Jason Bateman, who brought his 11-month-old daughter Maple. “Charlize is the nicest person on earth. She’s gorgeous and relaxed and sweet.”

Rumor has it, she’s also an amazing mom!

“Charlize absolutely adores [Jackson]. They have the most wonderful relationship,” the insider gushes to Us. One sweet example of her maternal instincts? “[Jackson] was jet-lagged, so when everybody sang ‘Happy Birthday,’ they had to whisper it. She didn’t want it to be really loud.”

Love it!

Photo: FameFlynet

Tags: birthday actors, celebrities, Charlize Theron, children, family, movies, set, son