Kirstie Alley says spending Christmas with her grandson was "stupendous and exhilarating"
Credit: D Dipasupil/Getty Images for Extra

Christmas this year was filled with a little extra cheer for Kirstie Alley.

The Jenny Craig spokeswoman, 66, celebrated the holidays for the first time as a grandmother, and says being able to spend Christmas with her then 6-month-old grandson Waylon Tripp Parker was “amazing.”

“My son [William Stevenson, 24] and his girlfriend came to work for me for three months, so I had my grandson with me for three months and it was nothing short of stupendous and exhilarating,” Alley tells PEOPLE.

“When I got up in the morning, as soon as that baby was up, I was holding that baby, traipsing around with him and showing him all the Christmas lights and singing to him.”

RELATED VIDEO: Kirstie Alley Reveals Her Secrets to Keeping Her Weight Off

Alley spent the holidays in Wichita, Kansas, with her father, son and grandson, and says it was an experience she’ll always treasure.

“We took photos of the four generations: my dad, me, my kid and the baby. I was dying to do that,” she says.

The Scream Queensstar has enjoyed being able to see her son through new eyes as a parent himself.

“It’s heartwarming to see your own child have a child,” she says. “My son and his girlfriend are amazing parents. I couldn’t have dreamt of anyone being better parents. I always knew my son would be because he loves babies, he’s always loved little kids, they’ve always gotten along really well with him.”

She adds, “He’s just an excellent dad, really hands-on. Both of them are just amazing.”

For more on Kirstie Alley’s morning routine, pick up the latest issue of PEOPLE, on newsstands now.