On Friday, the Waitress star, 35, shared three photos of herself partying on a boat in Mykonos, Greece. In the set, McPhee rocked a neon tutu, a sequinned hair bow and numerous other colorful accessories.
“Honey this is how you throw a party in Mykonos bitch!!” she captioned the fun-filled photos.
Husband-to-be Foster, 69, could also be seen partaking in the yacht celebrations in since-deleted posts on McPhee’s Instagram Story.
In an exchange captured by Comments by Celebs, the music producer’s daughter, Sara Foster — who, along with sister Erin, is known for leaving cheeky comments on her future stepmom’s posts — commented on McPhee’s post, “Yaaaaaaaas bitch. I mean, mother.”
The couple has been embarking on a whirlwind European vacation, both posting photos from Lake Como in Italy earlier this week.
A post shared by Katharine McPhee (@katharinemcphee) on Jun 21, 2019 at 11:37am PDT
Though it’s unclear when the couple plans on tying the knot, they were seen taking out a marriage license at a Beverly Hills courtroom in May.
However, a source told PEOPLE at the time that “ no ceremony.“
A post shared by David Foster (@davidfoster) on Jun 17, 2019 at 11:02am PDT
McPhee and Foster got engaged last July while they vacationed in Anacapri, Italy. This will be the second marriage for the American Idol alum, who was previously married to Nick Cokas, and the fifth for Foster, who was most recently married to Real Housewives of Beverly Hills star Yolanda Hadid.
In preparation for their nuptials, McPhee was surprised with a wild bachelorette party by her friends and Waitress costars in May, which even included a stripper dressed as a firefighter.
“Not your average meet and greet,” McPhee, who proudly wore a bride-to-be sash, joked.
The couple first met in 2006 when Foster mentored McPhee and other contestants on season 5 of American Idol, and after reconnecting, kept their relationship quiet in the beginning. But since getting engaged, they can’t help but rave about one another.
“We’re so happy and proud of each other,” McPhee gushed to PEOPLE at the Breast Cancer Research Foundation’s Hot Pink Party in May.
Last fall, she shared a similar sentiment, telling PEOPLE in September, “We genuinely love and respect each other and have for a very long time.”
Foster added that despite his and McPhee’s age gap, they bonded over being in the music industry. “We understand each other,” the Canadian songwriter said.
McPhee added of their relationship, “It doesn’t make sense to a lot of people, but it does to us.”