Blake teamed the look with a floral clutch and sky-high silver heels.
However the pregnant star clearly had enough of the heels because later in the night she ditched the stilettos in favour of a comfy pair of sneakers!
"Milkshake: check. Comfortable shoes: check. Having a slit in your dress to make you feel better about the aforementioned: check," she wrote on Instagram.
Blake posted a number of photos from the event, including her first-ever selfie with Ryan Reynolds.