Mandy Moore Shares Last Family Photo of 3 for New Holiday … – PEOPLE

Mandy Moore can’t wait to be a family of four this holiday season.

While speaking to PEOPLE about her partnership with Gymboree for its Holiday Capsule Collection launch, the actress, 38, says she’s “excited” to introduce and experience all the “quintessential” parts of the holidays this year with son Gus, 18 months, and her baby boy on the way.

“The holidays are fantastic just in and of itself, but the idea of being able to live through your children’s experience now, it’s the best. There’s nothing like it,” says Moore, who is expecting her second baby, another son, with husband Taylor Goldsmith.

“We’re just starting our traditions,” she continues. “With Gus being a little bit older and then having the new guy in the picture this year, it’ll be fun to start to pinpoint what exactly we’re going to do as a family unit.”

“I love the quintessential parts of the holidays like baking and decorating cookies and decorating the tree and planning family and friend get-togethers,” the This Is Us star adds. “Obviously, most things revolve around food, but anything that really gets you in the holiday spirit is something I’m excited to introduce and experience with my kids.”

Moore, Goldsmith and Gus recently had the opportunity to model Gymboree’s holiday collection in what was the star’s final photo shoot as a family of three.

Never miss a story — sign up for PEOPLE’s free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories.

Chris Garrison/The Childern’s PLACE/Gymboree

“I’m a sucker for holiday plaids,” Moore admits. “The fact that there are these adorable pictures of Gus and Taylor in the same plaid print, they’re wearing the same little button-down shirts, it just knocked my socks off.”

The soon-to-be mom of two also praises Gus for being a “really good sport in getting dressed up” for the shoot.

“He’s 18 months old and getting him to not only just sit still and not run around the room like a maniac is one thing, but he was such a good sport wearing the cute little reindeer antlers with the family pajama pictures,” she shares. “It was so much fun.”

The actress is also joining Gymboree in its effort to give back to communities in need, extending her role as a brand and charitable ambassador.

“Learning about all of the work that [Gymboree] does to give back to children specifically in underserved communities was something that really just resonated with me and stood out with me,” she explains. “I wanted to be more involved and proud to be a part of their commitment and furthering work, especially around the holiday season.”

“And to be able to marry that with our last photo shoot as a family of three, being able to include my husband and Gus in a project is so fun,” she adds. “These things just don’t come around very often. All of that combined is so exciting.”

For more on Mandy Moore, pick up the latest issue of PEOPLE, on newsstands Friday, or subscribe here.