Danica McKellar Adorably Bickers With a Former Flame in Hallmark's 'Love in Design' -- Watch! (Exclusive)

In a chat with ET, Hallmark star Andrew Walker previews the upcoming original movie

Danica McKellar is headed back to Hallmark Channel 

In Hallmark's original movie, Love in Design, McKellar plays home makeover TV star Hannah, who is sent to her small New England hometown to renovate the historical Lewisburg Manor for her show amid pressure from up top to revamp her show. When old flame, architect Jeff (Andrew Walker), is assigned to make sure Hannah's design preserves the historical manor, the two must find harmony between the old and the new. 

According to Walker, casting McKellar as the leading lady for the movie -- which he helped develop with executives at Hallmark for two years -- was an easy decision when they got wind that the Wonder Years alum had a gap in her schedule. "She's one of a kind," Walker, who's starred in a dozen Hallmark movies, tells ET of his co-star, before recalling an impromptu four-hour rehearsal he and McKellar had the day before production began. Watch ET's exclusive sneak peek above.

"I called her up on Sunday morning and I said, 'Hey, do you want to get together and work on [the movie]?' and immediately when I went over to her hotel room that afternoon to work on our material, she was so kind. We did these acting exercises, where you stare at each other and you do face recognition. We told each other things we felt that we were uncomfortable with, like things we didn't like about ourselves," Walker shares. "I joked that I wasn't the producer on this; if anything, Danica was the on-set producer on this movie. I've never worked with an actress who takes more notes in the morning and marks up her script more than Danica does. She sits in her makeup trailer and going through every line and questioning every single thing she does."

Their off-set chemistry shines through in front of the camera. Walker, a self-proclaimed HGTV fan, revealed the key scenes from the film he deemed most memorable to film with McKellar.

"I loved the scene where we leave the viewing with all the town comes to see our first episode and I sneak off into the swing set. It's when we start talking about real stuff and we connect. It's the first scene where we really do connect on a deeper level. I also like the scene where we start dancing in the rotunda in the backyard," Walker says, adding with a laugh: "But the moments behind the camera, we always joke that we didn't know what was the real camera crew or what was the fake camera crew."

A noted Hallmark vet, Walker expressed gratitude for his ongoing partnership with the network and explained why he believes the network's appeal continues to grow.

"These are stories that are relevant right now. People want to hear nice stories. They want to be able to sit in front of the television and not just watch people killing each other. It's something the climate of the world, the time that we're in, [calls for]. It always goes back to tradition, something that feels good for people, and the quality is unparalleled," Walker notes. "There's also a sense of an understanding of what you're getting yourselves into when you're watching one of these movies."

"Hallmark is allowing families to come together again, sit down as a family unit, watch these movies and feel good. You walk away with a great message, you might learn a little something here or there and you're entertained," he adds. "That's the niche that they have right now."

Love in Design premieres Saturday, Sept. 15 at 9 p.m. ET/PT on Hallmark Channel.