Sarah Chalke's Son and Daughter Are 'Very Different': It's Been 'Cool Getting to Parent Both' a Boy and a Girl

"It's crazy to me how a 1-year-old can make you laugh," actress Sarah Chalke told PEOPLE of her daughter Frankie Saturday at the premiere of Cars 3

Photo: Jesse Grant/Getty

Sarah Chalke is a mom of two now — and she says her 13-month-old daughter Frankie has been making that experience pretty entertaining as of late.

“She’s fantastic. I’m so in love with her,” the Scrubs alum, 40, told PEOPLE Saturday at the premiere of Cars 3 in Anaheim, California. “It’s crazy to me how a 1-year-old can make you laugh. She sits at the head of the table and she holds court.”

Continues the star of her daughter‘s current antics, “She knows what a donkey says: ‘hee haw.’ She cheers with her arms in the air, and she says ‘Wow,’ and she makes this really crazy face and then she’s like, ‘I’m out.’ ”

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Chalke says her children are “very different human beings,” and while it’s “been cool getting to parent both” a boy and a girl, she didn’t always envision her life as a mom quite that way.

“When I initially found out I was pregnant the first time, I just assumed it was going to be a girl because I come from all girls,” says the actress, who is the middle of three daughters. “I was thinking like, ‘A boy? What do you do with a boy? I don’t know how to do that.’ ”

But now? “I can’t imagine not having gotten to parent a boy,” admits Chalke, whose son Charlie Rhodes is 7. “It’s Lego structures and lightsaber fights, water balloon fights after school and ice hockey.”

“I just tried to learn how to play ice hockey. I was like, ‘He’s 7, I’ve got to keep up.’ I never learned to skate. I’m Canadian, and I’m sad to say [that].”

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The veteran actress, who will star in an as-yet-unspecified role in Netflix’s Roseanne revival (“[Lecy Goranson]’s going to be Becky,” Chalke says], confesses that figuring out sleep after baby number two has been “a learning curve.”

“It was a long time ago that I had an infant, and it was a lot easier [to get] no sleep then than it is now,” says the mom of two, who is engaged to Frankie and Charlie’s dad Jamie Afifi, an entertainment lawyer.

It’s worth it for Chalke, though, who couldn’t imagine her family any other way. “I feel like I didn’t know what [parenting] would be like with both, and really, it just feels like she’s completed everything,” the How I Met Your Mother alum says of her baby girl.

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The whole family was psyched for the movie, which Chalke says executive producer John Lasseter told her featured a “a very female empowerment story.”

“We’re huge Cars 1 and 2 fans,” she shares. “My son only wore Finn McMissile and Lightning McQueen underwear for about a year. His 2nd birthday cake was a Finn McMissile cake.”

She recalls, “First thing he ever wished for from Santa was Mack, because it was in two parts. He was like, ‘I’m wishing for the Mack trailer and the Mack front.’ He wanted to make sure Santa didn’t drop the ball and just bring part of it.”

• With reporting by SCOTT HUVER