09/22/2009 at 03:00 PM EDT
her first child later this year, Leelee Sobieski has a theory when it comes to her pregnancy cravings.
"I think I like eating what little kids eat," Sobieski told PEOPLE at the season opening of the Metropolitan Opera on Monday in New York City.
Chowing down frequently on macaroni and cheese, Sobieski, 27, says that she is preparing for the baby by doing two things: relaxing and eating lots of ice cream. However the Joan of Arc
actress is unable to eat as much of the frosty treat as she used to.
"I eat less ice cream now than I did before because the baby takes up space," she explained.
After announcing her engagement
to fashion designer Adam Kimmel this past July, the Emmy-nominated actress says that while wedding planning has taken a backseat to baby planning, it has not been forgotten.
"We have pushed that back," she said about her nuptials. "We are going to maybe do it in the spring."
For now, Sobieski – who is due in December – is staying focused on her upcoming arrival. She and Kimmel are keeping the sex of the baby a surprise, but teases "even if I find out, I'll keep it secret!"