"Everybody brought their family [to set]," the actress, 43, told PEOPLE at Grown Ups's New York premiere Wednesday night. "Valentina had the best time out of anybody on the set, I think."
What did her young daughter do to keep entertained while mom was filming? She serenaded Hayek's costars.
"She does sing 'Twinkle, Twinkle [Little Star],' but the kids [in the movie] taught her other [songs]. Now they've got her into the soundtrack of Mamma Mia. She of course likes [the song] 'Mamma Mia,' but she also likes 'Honey, Honey.' "
With such musical abilities, Hayek says her daughter may have a future in showbiz, though she "wasn't hoping for that."
Another Grown Ups costar, Madison Riley, who plays Rob Schneider's daughter, says Hayek's daughter is full of charisma. "She's also a spitfire like her mom," she tells PEOPLE. "She's gorgeous, sweet and she walked around in a little strut."
And even the grown ups were charmed by her.
"Salma always says, 'Oh, [Valentina's] got a crush on you," David Spade says. "She doesn't – but it makes me go 'ohhh,' and I'm nicer to her!"