Portland-raised artist Grace Mitchell quietly celebrated her 18th birthday in August by having dinner with a good friend at a restaurant in Hollywood, a city she has been visiting since she was 13 — initially accompanied by her mother, to write and record music.

“So just being in L.A. was pretty much the biggest birthday gift of all, because I live there currently,” she says of the showbiz mecca, where she tracked the eclectic EP “Raceday” for Republic and is completing her 2016 debut disc for the hip imprint.

The flame-haired folk-rocker knows how unusual her situation is – being allowed to leave the family nest at an age when most kids are struggling with SATs and senior proms.

But once she began composing at age 8, says Mitchell – who plays The City this week – her parents took her seriously, and enrolled her in choir and paid for piano, guitar and drum lessons.

“I think my mom probably wished that she could have pursued music or entertainment of some sort, so my folks were always really supportive, and they always motivated me to continue to pursue music,” she says.

Mitchell’s first song, called “Unified,” was awkward. “It was really cheesy, and it was about community and coming together and peace,” she recalls, sighing.

But soon, under the wing of a guardian, she was flying to L.A., and co-writing with Morgan Taylor Reid, a record producer responsible for Backstreet Boys hits. Together, they arrived at a sleek, often minimal sound in remarkable early cuts like “Your Design” and “Broken Over You.” She was discovered after posting her work on SoundCloud.

Mitchell saw herself as Reid’s apprentice. “He’s got a really serious history in music, and he’s also really inspired by pop,” she says.. “So he knows, algorithmically, how to make music, which I think is really fascinating, He has a formula for making a really good pop song, and he taught me how to make something abstract from that.”

That might account for the vocalist’s first big break, a languorous take on Hall and Oates “Maneater” for 2013’s “The Secret Life of Walter Mitty” soundtrack. She’d love to one day appear alongside Daryl Hall on his TV show “Live From Daryl’s House.” “He just seems like someone that you can really relate to on a creative level,” she says.

Now, the free spirit has encountered just one little problem with California independence.

“I’m super annoyed by the fact that I have to buy my own food now, buy my own everything,” she says. “I forgot that your parents do that for you, but only when you’re young!”

IF YOU GO
Class Actress, with Grace Mitchell
Where: Rickshaw Stop, 155 Fell St., S.F.
When: 9 p.m. Dec. 18
Tickets: $15 to $17
Contact: (415) 861-2011; www.snagtickets.com