updated 08/09/2014 AT 11:00 AM ET
•originally published 08/09/2014 AT 12:10 PM ET
Make a wish!
And what a surprise it was: Two-dozen partygoers – including Murray’s sister, Stephanie, and former The Bachelor contestant Kelly Travis – hid in an upstairs private dining room at Del Frisco’s Grille.
At around 8 p.m., Dorfman, 27 – wearing a white sleeveless top, skinny black leather pants, a statement necklace and nude high-heeled sandals – held Murray’s hand as she led him in for the big surprise.
An eyewitness tells PEOPLE Murray, whose birthday falls on Aug. 12, was overheard saying, “I had no idea – I’m completely shocked!”
The cocktail party included loads of drinks (beer and wine were flowing aplenty) as well as hors d’oeuvres that included pimento-cheese fritters, cheesesteak egg rolls, edamame, black-eyed-pea hummus and an array of the restaurant’s signature flatbreads (roasted tomato, pesto chicken, wild mushroom and garlic shrimp).
“It seems like this is the first time some of their friends are meeting each other,” an onlooker observed to PEOPLE.
The bride-to-be had the night all planned out, down to a cake from well-known Atlanta bakery Piece of Cake, made with vanilla layers and chocolate frosting and topped with 30 sparklers for candles.
After the group sang “Happy Birthday” to Murray and enjoyed the delectable dessert, the couple left together at 11:30 p.m., off to the next secret location, The Painted Pin. About 20 friends were waiting with two reserved lanes at the newly opened bowling alley and lounge to yell Surprise!
The group toasted with Moscow Mule slushies, and Murray blew out 30 candles on his second cake of the evening, an orange bowling ball cake from Cherry on Top Delights bakery. Murray’s sporty past came in handy, as a source tells PEOPLE, “He showed Andi some bowling tips and even got behind her, showing her how to bowl.”
Murray and Dorfman had such a good time dancing to a live band, bowling, playing pop-a-shot basketball and kissing that they stayed past closing until 2:30 a.m. They left the same way they arrived to both events: together.