By Jesse Spero

LOS ANGELES, Calif. --

You might recognize Amanda Seyfried as a member of “The Plastics” from 2004’s “Mean Girls” or as part of the unconventional Henrickson clan in HBO’s “Big Love,” but the world is about to see — and hear-- a whole new side of the young actress.

Access Hollywood caught up with Amanda at the “Mamma Mia!” premiere in New York City as the actress found out the news that she’d been named AccessHollywood.com’s latest Rising Star.

“I don’t believe it! I don’t know that I’ll ever believe this is all happening, cause I’m just floating,” she exclaimed. “It’s really amazing, my dreams have come true and now to see my face all over the Internet would be awesome.”

When Amanda found out one of film’s greatest actresses, Meryl Streep, was cast in the ABBA-inspired musical, Amanda set her sights on landing the role of Sophie. And even after finishing “Mamma Mia!,” she’s still in awe of her co-stars.

“I can’t believe that I was sitting on Meryl Streep’s lap! And she was painting on my toenails. I had the best on-screen mother that I will ever have,” she told Access.

Amanda says she was able to draw upon Meryl’s wisdom and experience while they filmed together. She hopes this isn’t the last time she’ll work with the acting powerhouse.

“She knows what it’s like for a young person to come into this opportunity, she knows how to deal with it " Amanda said of her “Mamma Mia!” mom. “She made me feel so great and so relaxed. I couldn’t have asked for anything better. I want to work with her again.”

Singing ABBA’s music is not the first time Amanda has proved her musical skills, but she told Access she decided early on to put her acting career ahead of her musical aspirations.

“Singing was my first passion,” she told Access. “I connected to it very intensely as an adolescent. It was my love and then I moved to New York and started acting full time.”

As for the possibility of Amanda turning into a full-fledged singer now that the world is hearing her sing the beloved music of ABBA, she says that’ll happen only if the Swedish supergroup’s Benny Andersson is involved.

“I do think about it with Benny, and I don’t think I would do it with anybody else,” she said. “But I don’t think I want to go down that path, I want to stay focused on acting. But with Benny, if he makes anything, I’ll sing it!”

Amanda might not want to transition into the world of pop music right now, but she already has one person who will line up to buy her album and watch her perform.

“Isn’t she fantastic!” Meryl Streep told Access. “She’s the one who should have a recording contract in my humble opinion. She could be a rock star.”

Next up for the actress/potential-rock star, is the third season of HBO’s “Big Love” and Diablo Cody’s zombie movie, “Jennifer’s Body,” where Amanda will co-star with Megan Fox.

Amanda told Entertainment Weekly that fans have a lot to look forward to when she teams up with the “Transformers” hottie.

“We make out in one scene,” she told the mag. “That’ll probably be the trailer… in slo-mo.”

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