"Nick, Emme, and I are so excited to finally share this news..." she captioned the pic.
In the collage, the couple pose with their precious 2-year-old daughter, Emerson, holding a pair of baby shoes. In another photo, the super cute tot stands in her crib with a sign that reads "Eviction Notice."
The 36-year-old "Once Upon a Time" alum and the Atlanta Braves player, who welcomed their first child back in May 2013, revealed to PEOPLE magazine that they are expecting another girl.
"We are so excited that our family is growing and can't wait to meet baby number two,” the pair said in a statement. "[Emerson] keeps telling us she's going to teach her little sister 'everything she knows' ... so we are counting on another expert on all things Princess Elsa, ponies and Play-Doh!"
"The best advice I have ever received is to trust your instincts and make sure to take care of yourself, too" she said. "When I first had Emme, I was so focused on doing everything 'right' or 'by the book' that I forgot to listen to my gut and have confidence in that."