04/23/2012 AT 6:00 AM ET
The Academy Award-winning actresses took in some girl talk over dinner at Chateau Marmont in West Hollywood, where the two “genuinely [appeared] to have fun with one another,” an onlooker tells PEOPLE, adding that Theron sipped on wine, while expectant Witherspoon drank sparkling water.
Theron, who sported a white blazer and jeans with her hair pulled back, was all smiles, according to the source, who says Witherspoon was glowing in a casual short dress.
After greeting friends who approached the ladies’ table throughout their meal, Theron and Witherspoon called it a night around 10:20 p.m. and headed to pick up their cars from the valet.
– Jessica Wedemeyer