Who would have expected this from Cindy Lou Who?

Child star and current “Gossip Girl” actress Taylor Momsen has come a long way from the 2000 film “How the Grinch Stole Christmas.” Although no one else saw her rock transformation coming, she always did.

“Rock ’n’ roll is what I grew up with. It’s what I love,” she said. “It’s something I’ve been drawn to since a really young age, and this band is something I’ve always planned on doing.”

It’s hard to believe Momsen was listening to Soundgarden and System of a Down offset while filming “Spy Kids 2,” but she claims it’s true. One White Stripes show kicked her Britney Spears habit, and Momsen has been a rocker at heart ever since.

She’s not going about it like most actors moonlighting as musicians. She writes and plays the gritty, hard rock she loves with three hairy dudes, hides under the name The Pretty Reckless instead of striking out solo, and is touring the country at small clubs, like Sunday’s show at The Conservatory.

Of course, this method has been meet with reservations from fans of Momsen’s acting and modeling who are more likely to listen to Katy Perry than Korn.

“It’s been mixed,” she said. “People who give it a chance tend to like it, but I think because of the show and everything, there aren’t a lot of people who give it the time of day. It’s something to overcome, and it’s a challenge we face, but hopefully people give it a try. They might be surprised.”

Now that her debut album, “Light Me Up,” has come out stateside, Momsen hopes that the time she spent crafting the record pays off. She certainly works more than a typical 17-year-old, so excuse the thick mascara and shadow around her eyes — it’s just masking the lack of rest.

“The album was written and recorded kind of simultaneously, and I was also filming ‘Gossip Girl’ at the time, plus modeling, so I pretty much didn’t sleep for a year,” she said.

Momsen is serious about the music, and it has taken precedence over everything else. She’s taking a break from “Gossip Girl” while she tours, and although she plans on returning, doesn’t know when or how much acting will be involved down the road.

“I’d like to think I’m now a singer who also acts,” she said. “Acting and modeling, I enjoy them, but they are jobs. I’m just so happy when I’m writing, performing and recording music.”

Ironically enough, Momsen might have still been an actress/musician had things gone a different way. She tried out for the title role of “Hannah Montana” and was down to the final three before the part went to Miley Cyrus. It certainly would have thrown a wrench in her plan for hard-rock stardom, and now Momsen knows things happen for a reason.

“Who knows what would have happened?” she said. “I try not to think about it, honestly.”