The Roaring ‘20s took on a whole new meaning for Gossip Girl star Blake Lively who celebrated her 21st birthday with a flapper-themed party at the New York Palace Hotel in NYC on Sept. 6.

And while Blake often films scenes from her series at the hotel, this time the actress played the role of director. “I love to plan parties,” Blake tells Life & Style. “That would be my career if I weren’t an actress.”

Blake’s high school friends and family were among the crowd, which also included Gossip Girl co-stars from Chace to Leighton, A-list pals like James Franco, and crooner Michael Bublé, who sang “Happy Birthday” to Blake. (She toasted with Coca-Cola instead of the night’s signature Möet peach mimosas.) But the birthday girl had someone else to melt her heart boyfriend (and co-star) Penn Badgley. “They were very cozy,” an insider tells Life & Style who attended the party. “They seem as if they’ve known each other forever.” What more could Blake wish for!

"The party was a great success, everyone really got into the 1920's theme," H. Tony Berger of Relevent (who produced the event) tells Life & Style.