Scarlett Johanssonis soaking up some sweet moments with her “gummy” kids.

During a recent chat with herSing 2costar Reese Witherspoon for PEOPLE, the actress, 37, who is mom to 4-month-old sonCosmo, whom she welcomed in August with husbandColin Jost, and to daughter Rose, 7, with ex Romain Dauriac, shared that Rose recently hit a very cute milestone.

“My daughter just lost both front teeth and it’s really, really hilarious and funny,” Johansson says in the latest issue. “Just watching her eat pizza is, it’s a whole thing.”

George Pimentel/WireImage

Scarlett Johansson; Reese Witherspoon

“Christmas card!” Witherspoon suggests (as potential good use of Johansson’s “toothless” kid photos).

Subscribe to our new 12-episode weekly podcast,Me Becoming Mom,to hear celebrity moms open up exclusively to PEOPLE about their extraordinary roads to motherhood.

ROBYN BECK/AFP via Getty

Scarlett Johansson

“He’s great,” Johansson said recently. “Making all the fun discoveries like feet. It’s the best. I mean, feet, who knew? There they are. Life-changing.”

Vivien Killilea/Getty Images

Colin Jost; Scarlett Johansson

Ahead of the release ofSing 2, the actress says she was happy to return to voice her spunky porcupine character, Ash, especially because theSingmovies are the only ones her daughter is allowed to watch at the moment.

“I think Ash just has a really great sense of humor. She’s very dry,” says Johansson. “I like her quirks, she’s very dry and funny.”

For more on Scarlett Johansson and herSing 2costar Reese Witherspoon, pick up the latest issue of PEOPLE on newsstands Friday

Sing 2

She is also still shocked her work in the sequel involved singing a song with U2’s Bono, who plays a new character, reclusive rockstar lion Clay Calloway.

“[It’s] totally mind-blowing. I couldn’t have imagined a situation where we would be doing a duet, or certainly a duet that anybody would ever hear,” says Johansson. “Maybe like a duet at 4 in the morning at some random hotel bar or whatever. But not on a soundtrack.”

Adds Witherspoon: “I imagined you went to his castle somewhere and that there’s a recording studio in this castle. Doesn’t he live in a castle?”

“I feel like he should,” says Johansson.

Sing 2opens in theaters Dec. 22.

source: people.com