Cowell, who told Us Weekly in August that he was "happy and excited" about becoming a father, helped organize the event at his house in Beverly Hills but left before Silverman's guests arrived. Among the 20 or so all-female invitees? His ex-girlfriends Mezhgan Hussainy and Terri Seymour.
The ladies were treated to an English tea party-themed bash in Cowell's back garden, complete with mini sandwiches, cakes, and tea. (Wine and champagne were also provided for those who could drink.)
After lunch, Silverman opened gifts for herself and her little boy. "He's already got a wardrobe to rival any A-lister," a source told Us of the impressive haul. "There were piles of beautiful newborn clothes -- plenty of hats, super-soft onesies...someone had bought him a tiny pair of shoes, too."
Silverman, for her part, seemed to be in great spirits throughout the party. "She had her hand on her tummy a lot," the insider said of the second-time mom-to-be, who has a son, Adam, with her ex-husband. "She kept rubbing it, and she looked really proud."
Her British beau was beaming, too, when he returned home shortly before the party ended. "They seem to really be in love," a source told Us of the couple, who confirmed their baby news while Silverman was still married. "I've never seen him like that before."
