Mariska Hartigay(Photo: Brian Bowen Smith)

It took years. It almost broke her heart. Here, for the first time, Mariska Hargitay shares the tender story of how she adopted her two precious new kids

Mariska Hargitay is among America's favorite (not to mention highest-paid) TV actresses for one very good reason: her portrayal on Law & Order: Special Victims Unit of Olivia Benson, the grave, rarely smiling but deeply compassionate sex-crimes detective.

So it's happily jarring to enter Hargitay's sprawling but comfy New York City apartment and find...the trappings of a party. Dozens of helium balloons bounce against the ceilings of the living room and office; it was Hargitay's 48th birthday recently, and her husband, actor Peter Hermann (who recently starred in the Broadway play War Horse), surprised her with a hayride-themed party. While the bales of hay have thankfully been removed, those balloons remain a happy reminder of the soiree. A massive teddy bear is also a permanent fixture in the living room.

"This is the fun house!" Hargitay says, buoyant in a Manhattan mom's outfit of black jeans, riding boots, and layered tees that reveals her to be, refreshingly, as normal-size around the midriff as any top actress dares to be.

Hargitay has had quite a year. She and Hermann adopted a baby, daughter Amaya, now 14 months, and six months later she stunned the public by taking home a second baby, Andrew, now 10 months old.

Now in the kitchen, Hargitay and the whole family are crammed around a long table, having a lunch of Ethiopian chicken, rice, vegetables, and bread. "We like trying new cultures," she explains, bouncing Amaya — a chocolate-skinned cherub in a birthday-party — worthy dress — on her lap before handing the little girl across the table to tall, handsome Hermann, who cuddles his daughter with enormous tenderness. Skim-milk — pale and with eyelashes to die for, baby Andrew is being cradled in his nanny's arms. At the head of the table is the happy-as-a-clam big bro, August, in the Batman skullcap that rarely leaves his head (it has to be pried off at bedtime). Hargitay and Hermann's biological son, who is nearly 6 years old, obviously relishes his newly expanded family.

"August thinks this was all his idea!" Hargitay says, with a husky laugh. "He said, 'I want a baby sister,' and Amaya came. Then he said, 'I want a baby brother,' and Andrew came. August is feeling pretty good and pretty powerful!"

This is the peppy, straightforward, smiling Hargitay — the un-Olivia, in fact: a woman whose bursting-full life is perhaps not easy, but certainly a source of great joy. Yet the qualities that give her performance as Detective Benson such haunting resonance are just a heartbeat away. As the younger children go for their naps and August heads to his room to play, a more emotional, deeply thoughtful Hargitay comes out. "I'm not gonna lie," she says as she launches into the story behind her burgeoning family. "There were wrenching moments. I say to everybody, 'Adoption is not for the faint of heart.' "