Ashton Kutcher shares his family's sweet birthday tradition

Ashton Kutcher is looking forward to a sweet treat on his birthday and no, it's not birthday cake.

"We have a family tradition," the actor explained Monday on "Good Morning America." "I'm gonna fly home tonight so I can wake up tomorrow at home because in our family, breakfast is the most important meal on birthdays. We do this pancake cake and so it's a tradition [Kutcher's wife] Mila [Kunis] started years ago before we ever had kids, where every morning, somebody gets like a jumbo stack of pancakes with sprinkles on them and a candle."

Kutcher, who turns 45 on Tuesday, dropped by the "GMA" set with his "Your Place or Mine" co-star Reese Witherspoon.

Witherspoon and Kutcher are the two leads in Netflix's latest romantic comedy that will be released ahead of Valentine's Day on Feb. 10.

"Your Place or Mine" follows Witherspoon as Debbie and her longtime best friend, Kutcher's Peter. When the duo decide to house swap -- with Debbie in New York City and Peter in Los Angeles -- for a week, the two opposites unexpectedly get a peek into what their lives could be if they got together, according to a teaser synopsis.

Although the two stars have been in romantic comedies before, "Your Place or Mine" is their first together and Witherspoon was the one who approached Kutcher about the project, who quickly accepted.

"This script is amazing," Witherspoon told "GMA." "It's written by Aline Brosh McKenna, who wrote 'The Devil Wears Prada' and '27 Dresses.' It was like, we both are such big fans of hers. So when we read the script, it was just perfect. It felt modern, it felt fresh, it didn't feel old or tired and it's also got single moms and having a second chance at love."

To prepare for their new roles with characters who lived on opposite coasts, Witherspoon and Kutcher said they started video calling each other a month before filming began.

"We had to pretend to be friends for 20 years. So we started calling each other and FaceTiming each other for about a month ahead of time," Witherspoon said. "So it was really good. By the time we got to set, I knew his favorite football team, the name of his dogs."

"We got real close. I mean, with mom on the porch," Kutcher continued. "It was actually really cool because we're only in three scenes where we're physically together. And so building this chemistry and building a relationship and really becoming genuine friends, it made it, once we started filming, because most of the time we're filming, one of us was just FaceTiming in while the other one was on set, and so it was just natural because we're already communicating that way."