The “Mother’s Daughter” singer, who has been recovering from vocal cord surgery in Tennessee, spent time with the Australian musician, 22, to celebrate her special day.
Cyrus was spotted seated next to Simpson at what appears to be a celebratory meal in Nashville, according to a photo posted by a fan early Saturday morning. In keeping with the festive vibes, a variety of colored balloons adorn the table where Cyrus, Simpson, and several others are seated.
Keeping the birthday celebrations going on Saturday afternoon, the pop star shared a series of sweet video messages from fans, as well as a pair of throwback posts of herself from birthdays past. Seemingly getting the TBT memo, her father Billy Ray Cyrus also posted a vintage clip of the pair, as the country singer brought his baby girl along for one of his interviews.
“Happy Birthday @mileycyrus!!! Love you so much,” he captioned the cute clip.
Joining in on the birthday love, Miley’s mother, Tish Cyrus, posted a photo of her daughter from the set of the music video for “Don’t Call Me Angel.”
“Always and forever my angel… Happy Birthday MCzzyyyy! I love you,” she captioned the shot, which showed Cyrus playfully sneering in a pair of angel wings, while flipping off the camera.
While Cyrus has been recovering, the singer has been spending some time apart from Simpson, but a source recently told PEOPLE that things are still going well for the two.
“Miley and Cody have their separate lives,” the source said. “Cody had to stay in L.A. but has visited Miley in Tennessee. They have a very easy relationship. They see each other when they can, and when they are apart, things are good too. This works for both of them.”
When Cyrus was hospitalized for tonsillitis last month, she discovered a separate issue with her vocal cords, which she unknowingly had for years, according to sources. After learning of the issue, Cyrus was told she would need to have surgery before the end of the year, and that the recovery process would include several weeks of silence.
“Miley is recovering well,” the source added. “She still has to be careful about using her voice, though.”
A source close to Cyrus previously told PEOPLE, though, that she is “doing great and will be back and better than ever early next year.”
In early October, Cyrus and Simpson, who were friends for years before romance bloomed, made their romance official after they were spotted kissing during a breakfast date.
At the time, Cyrus was coming off of high-profile back-to-back breakups, first with husband Liam Hemsworth followed by a more recent relationship with The Hills: New Beginnings star Kaitlynn Carter. Cyrus and Carter, 31, ended their whirlwind romance in late September, while Cyrus and Hemsworth, 29, ended their seven-month marriage one month prior.
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“It is early, but their friendship is long-standing and deeper than people realize,” Simpson’s manager Matt Zeidman previously told PEOPLE exclusively. “Though they originally met during their own wilder phases, they’re both sober now and are focused on health, work and spending time together. Seems pretty ideal to me.”
Simpson echoed those sentiments to PEOPLE last month, saying he and Cyrus “found each other again in a space where we’re both not partying” and “working real hard.”
“Any girlfriends I’ve had in the past has always been immediate romance and so it’s a different experience having been friends with somebody before and it developing naturally into something more,” he said.