Attention, American Idol fans: Jason Castro’s jaunty major-label debut single, “Let’s Just Fall in Love Again,” premiered last night and is currently streaming at his Web site,

To celebrate the occasion, the season 7 third runner-up got on the phone with to discuss his songwriting process, his collaborators, and how he defines success.

EW: What I like about your debut single is that it’s really well-produced, but it doesn’t steamroll the intimate sound we’ve come to expect from you.

Jason Castro: That is definitely something from the onset that I tried to be aware of. You know how some of the Idol projects can turn into manufactured pop things? From my first meeting with Atlantic, I went in there and explained my vision and played for them — I wanted to get my deal off of my songs — and we were all just on the same page. We’ve been on the same page since day one. We decided to do the whole album with one producer, Eric Rosse, and we put a lot of love into it.

EW: So getting back to “Let’s Just Fall in Love Again”…

JC: The original demo was just acoustic, and we wanted to keep that same energy but give it some extra oomph — without losing the magic. That recording actually ended up being like a Frankenstein monster, but you wouldn’t know it. We had pieces from the original demo — the original guitar and the handclaps. We had to use the handclaps because they were really lively. [Laughs.] And when we recorded it out here [in L.A.] we tracked the whole thing, we used drum and bass from our session out here. And then we used a little organ and a couple other things from another session we did in New York.

EW: What about the whistling that starts the track? Where did you come up with that?

JC: It’s the melody from the chorus. It was going to be some line, maybe a guitar line — but the whistling just kind of stuck out. It felt like that kind of song. When have you heard whistling lately? So we were like “Let’s whistle it up!”

EW: Who’s doing the whistling? You?

JC: That is not me, you would be surprised! Don’t tell anybody! Everybody in the studio took turns. We can all whistle — but it wasn’t like that whistle. [Laughs.] That was the key to the project, finding a whistler.

EW: Did someone win the whistle-off?

JC: Somebody in the studio. And actually we brought in an outside whistler, and I don’t want to say it, but he couldn’t cut it. But I don’t want to talk bad about any whistlers around town or anything.

EW: Well, it’s out there now. Lyrically, the song has a real sense of humor: “We’ll fall disgustingly fast/ And we’ll start hanging out with friends/ And they’ll be so offended.”

JC: It’s a very playful song, and that’s kind of what it’s all about. Recapturing that playful time from when you first meet and everything’s great. And for some reason every relationship gets to a little standstill. We wanted to inspire that feeling of why are you wasting time doing anything else? Just have fun. Love life. Love each other.

EW: So let’s talk about American Idol for a minute. Were you initially upset when you finished the Idol tour last year and 19 Entertainment didn’t pick up their option to sign you?

JC: It didn’t worry me. I was like, “Okay there will be other opportunities.” Even if I didn’t get a major-label deal, I could have just done this as an independent thing. I mean, I had the opportunity to go play music and make a little living out of it — however small or large it is.

EW: You sound a little philosophical.

JC: That’s an accomplishment. I play music for a living, and that’s my dream. You gotta pay the bills! [Laughs.]

EW: Is there any sense of getting the last laugh by signing with Atlantic Records, given that the Idol judges never quite “got you” during season 7, that they seemed to be stuck in a Celine Dion bombastic rut and didn’t really appreciate your sound?

JC: That never bothered me. That’s just the way life works. I even thought that way myself — “I’ll never get anywhere, I don’t sing like these people.” But then there was something in my mind — maybe it’s about that time, maybe people would like something like me. Ultimately, the judges have their opinions. And I’m excited to show them what I’ve done — it’s not like we had something against each other — and I’m sure they’ll be happy for me. There’s no “last laugh” thing! [Laughs.]

EW: I’ve only heard the single thus far. Tell me about some of your other favorite songs on the album.

JC: I worked with Greg Wattenberg [Five for Fighting] and Marc Roberge [OAR] on a song called “This Heart of Mine.” It’s a pretty cool one, and it might be a contender for a followup single. It starts out as this real intimate acoustic thing, but it’s got kind of this groove, and then thechorus busts in, and the chorus is huge. This song to me is kind of an epic song, the way it builds into the chorus, and the bridge just soars. It’s a very cool progression, not like a lot of the songs I write, but this one just came out and kept on flowing and soaring to this place.

EW: Any songs you covered from your Idol season?

JC: “Hallelujah.” I never did a full recording of that and I just wanted to get one down. That song is a huge part of me, I think, even pre-Idol. I wanted to get that out to people.

EW: Any other songs to look out for?

JC: There’s a song that’s on my mind right now because I’m getting ready for a show on Wednesday at The Grove, and it’s one of the newer songs that I’ll be playing live for the first time called “It Matters to Me.” It’s one of the last ones I wrote, it almost didn’t make the record, but it wouldn’t get itself out of my mind. And it landed on the record and I love it. I’m really stuck on it right now.

EW: Did you write it with anyone?

JC: I wrote it with a guy named Jamie Kenney, and it’s just a very intimate, sweet song that has a lot of raw emotion. I’d gotten in a groove of writing upbeat stuff and this one brings it back down. I think this is one people will click with.

EW:Serena Ryder does guest vocals on a track, I hear.

JC: Yes, a song called “You Can Always Come Home.” She came in and did the vocals with me and it’s just beautiful. There are two-part harmonies throughout and an acoustic guitar. That one is special.

EW: What’s the writing process like for you?

JC: It usually starts with a melody. I like to get the melodies in place, and sometimes the melodies naturally have some words that stick out in them. So I’ll grab on to a couple words that fit well in the melody, and think, what does this relate to? And also, the melodies often have sentiments of their own. Then you start putting the pieces together. Sometimes a lyrical idea happens first, but that’s been more rare for me.

EW: You have your guitar with you when you write?

JC: Yeah, yeah, always the guitar. He’s my writing partner. He’s the one that makes me feel comfortable.

EW: So you’re on the brink of releasing your first album. What’s success for you?

JC: I don’t know what to say to that one, really. Commercial success would be a plus, but in this last year I’ve been reading so much about the music business, and right now it’s kind of being redefined, what it means to be successful. If I can play shows and people are coming to ’em, I’m happy. And if I sell 1 million records, I’m happy too. That’s where I’m trusting the label and their people. I do the music. They do the marketing stuff. I do need to hear my song on the radio once. You hear artists talk about the first time they heard their songs on the radio. I want to have that feeling. If that happens, that’ll be my little token!

(To get all my Idol-related scoop, follow me on Twitter @EWMichaelSlezak)

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