A few years ago, actress Amanda Peet was in Belfast, shopping for Hanukkah gifts with her longtime friend, Andrea Troyer, while their husbands were working. (Their husbands, David Benioff and D.B. Weiss, are co-creators of HBO’s Game of Thrones.) This might seem like a highly unlikely setting from which a debut holiday picture book would spring, but Dear Santa, Love, Rachel Rosenstein (Doubleday), co-written by Peet and Troyer and illustrated by Christine Davenier, grew out of the women’s conversation about Peet’s trouble explaining a Christmas-free existence to her kids.

“My kids were asking me, ‘Why can’t we have a Christmas tree?’ ” and I didn’t have a good answer because I always had a tree growing up, even though my mother is Jewish,” Peet said. “I was finding it very difficult to let Christmas go myself.”

The Peet-Benioffs are a family of five – two girls and a baby boy born last year – but they had decided as a couple that they would celebrate Hanukkah only.

Peet’s heroine, the eponymous Rachel, also belongs to an observant Jewish family, but what Rachel mostly observes is that Christmas seems way cool – the twinkly lights, the “gi-normous tree,” and the “store windows crowded with Santas, elves, candy canes, glittery tinsel, and piles and piles of presents.” What kid could resist?

Young Rachel goes right to the top in a letter asking Santa to visit “the brick house on Huntley Drive. YES. The one with NO holiday decorations,” explaining “I’ve been really good all year and I know that you are a fair person and will not mind that I am Jewish. After all so was Jesus, at least on his mother’s side.”

Peet said she often looks to books when she’s stuck on a parenting issue, and she was stuck on this one. “When you are growing up, you are constantly told how great Hanukkah is but you can’t help but develop something like an inferiority complex because however great Hanukkah is, it isn’t as great as Christmas,” she said.

But in this case, she couldn’t find a book with precisely the message she was looking for. So she turned to Troyer, a writer by trade, to help her craft it. “She’s one of my best friends, our children are the same age, and her husband is Jewish, too,” Peet said.

Peet had never written a picture book before, but she made her playwriting debut in 2013 with The Commons of Pensacola, which starred Blythe Danner and Sarah Jessica Parker in the lead roles. “I wrote a lot in college, really badly I’m sure, but then I got sidetracked by acting,” Peet said. “But the older I got, the more unsatisfying the roles I was offered were becoming. So I started writing, initially out of a desire to write something for myself, but it [also] became much more fulfilling to write for other actors and I’m lucky. I know a lot of actors.”

She even thought about returning to school for an MFA in playwriting, applying to UCLA. “But I didn’t get in and I couldn’t move to New York.”

Full-time writing will take a back seat to acting again as Peet prepares for the second season of Togetherness, a HBO comedy about four middle-aged professionals trying to reconcile their dreams with their reality. “I was actually starting to say goodbye to acting when this came along. I feel like I won the lottery. A role that is creatively fulfilling for a woman at age 43 is like finding a needle in a haystack.”

But she thinks she has at least one more picture book in the pipeline (her agent was in the processing of sending the manuscript out on submission at the time of this interview), and her kids are supportive of their mom’s new role: author. Frankie, her eight-year-old daughter even wants a piece of the action, Peet said. “She asked me, ‘Can I make the drawings in your next book?’ ”

Dear Santa, Love, Rachel Rosenstein by Amanda Peet and Andrea Toyer, illus. by Christine Davenier. Doubleday, $17.99 Oct. ISBN 978-0-553-51061-4