To get a measure of Rachel Sermanni you could do worse than search for her on YouTube.

Somewhere in that digital neck of the woods you'll find a video of the 20-year-old singer performing a stripped-down version of I Want You Back, Michael Jackson's finest moment and probably the greatest pop song of all time (we take that as a fact not an opinion round here. Only T Rex's 20th Century Boy comes close). In place of Jacko's youthful beseeching, though, Sermanni slows the song down and recasts it as a Scottish lament. As she sings her sweet, high voice soars and soars. Close your eyes and you'd imagine Joni Mitchell had moved from Laurel Canyon to Carrbridge.

In short, Rachel Sermanni can sing a bit. She can write a bit too. And talk. Boy, can she talk. We're in the Citizen M hotel in Glasgow a few hours before she drives north to Fort William to start recording her debut album and she's telling me the derivation of her name (Italian, although her grandfather reckons it's originally Middle Eastern), how much she loves the late American vocalist Eva Cassidy, why she wants to move to Amsterdam in the next 12 months, her memories of busking on the beach with Mumford & Sons and about her shadow side. She's bubbling with energy and enthusiasm, a fresh-faced, manga-eyed girl with hippy tendencies (her favourite novels are Herman Hesse's Steppenwolf and Siddhartha).

The word she uses to describe 2011 is "whirlwind". She toured Europe, supported Elvis Costello in Sligo and Rumer in Birnam. She can't believe it's been 12 months since she appeared as part of the New Voices strand of the Celtic Connections festival. "I feel it was much longer ago in terms of me as a person and a musician," she says. "It feels like I've developed. I suppose this is a job now. Maybe this has been the year of realisation of what I'm doing." And does she like the job? "I do; definitely."

Sermanni was born in Inverness and lived in Aviemore before moving to Carrbridge, the place she still calls home. "As much as I love the city, I'm so thankful I was brought up in the countryside. There's lot's of freedoms. I like the free-range feel of the hills." As a child, music was the stuff she heard in the car or in church or in the courses in traditional music she did during Easter breaks from school. At home she listened to Van Morrison and, of course, Eva Cassidy. "The one album that's resonated through my life has always been Songbird [Cassidy's 1998 compilation]," Sermanni says. "I know that album inside out but I still don't get tired of hearing it. I barely listen to it any more but I was always struck by how she sung. I think she's great. I've learned a lot of people have a different opinion, but I'm really fond of her and how she sings. I liked the fact she's really vulnerable in soul when she's singing. She puts everything into it and I like that."

Sermanni likes a lot of things. "I'm not much of a non-liker really," she admits. There's no cynicism in her. Maybe it's because she's still so young. Which may also be why she's so fearless too. After school she moved south to Glasgow to play music for a year with no real plans. She met Mumford & Sons at the Loopallu festival in Ullapool and asked to jam with them. And they said yes. "I sat on the beach and sang them a song and from there onwards it was just like this huge jam on the beach. The pianist asked me to come down to London. That was even before I'd moved down to Glasgow so it felt like a nice transition. I went and recorded a song and learned I could sing loud songs. I'd never written a loud song. That was really great."

Her own songs are all fresh breath and floral perfume, yet she says she is drawn to darker themes. The question is: what is her definition of darkness? Is it stealing fudge from Cineworld's pick-n-mix or popping down the opium den with Pete Doherty? Sermanni laughs and avoids the question. "I like the idea of shadows and things like that. I've been reading lots of dream books and they always talk about the adversary, the enemy in your dreams. There are loads of different terms for it but one of them is the shadow and I like that. Embracing that makes you far more balanced rather than convincing yourself you're really, really good. Because then the shadow will explode out of you. I think the shadow comes out a lot in songs."

Well, what's the personality of your particular shadow, Rachel? "It's probably a little more - devious. I'm a Scorpio. I don't know about horoscopes but my mum was always talking about how Scorpios can be sly and I understand that. Either being the eagle or being a lizard. It's very easy to be the lizard hiding underneath the rocks. It's easy to start to dwell. You've got to stay in the light otherwise you can easily dwell on things. But I do think that's part of everybody and it's good to embrace other people's darkness. I like people who are a bit harder to get on with sometimes than really, really happy people." OK, so we'll take it that darkness equals grumpiness then and that Sermanni's hippy leanings should be well and truly established now.

When she's not in Carrbridge or on tour you'll find Sermanni in Glasgow, maybe busking in Sauchiehall Street or hanging out at Bloc on a Monday night where Admiral Fallow's Louis hosts an open-mic night that attracts traddies, jazzers and indie kids. Then again, that might change soon. "I'd like to move to Amsterdam next year," she says. "I really like that place. It's got this arty feel and I've made loads of friends in Holland because that's the place we've been to most. And I think if I say I'm going to head to Amsterdam for a little while enough times it might happen. It's got amazing venues and they're huge music appreciators." She smiles and adds quickly, "It's not really the drugs I'm interested in."

So there you have it. The sound of young Scotland is drug-free but mentally tie-dyed. And it comes with a smile as wide as the Caledonian Canal.

Rachel Sermanni's Black Currents EP is available on February 6 from iTunes or Rachel Sermanni plays Celtic Connections on January 22 and Edinburgh, Aberdeen, Inverness and Glasgow in February.