Alyson Hannigan

"Luckily, my career is not based on my body. I play the quirky sidekicks, the offbeat characters. I’m not the boobs in a movie," she said, contrasting herself against some of the shapely actresses hired for the movie to make men salivate.

But Hannigan is a wallflower no more.

The scarlet-haired actress who played the good witch Willow on television’s "Buffy the Vampire Slayer" and flute-tootling band-camper in the "American Pie" movies has lately embraced her naughty side.

Hannigan shed her "American Pie" character’s googly-eyed plain-Jane dopiness in favor of girl-next-door seductive chic in the new sequel "American Wedding."

"Yeah, I didn’t have to geek out as much!" the 29-year-old exclaims with relief during a phone interview while driving through Hollywood for a fitting with her stylist.

"I’ve become a woman," she purrs, laughing. "I’m all growed-up now."

Consider the recent FHM magazine cover photo of her making smokey eyes at the camera while arching her back in skimpy lingerie.

"Whoo hoo hoo!" Hannigan coos playfully about the magazine shot. "Hey baby, that’s always fun to do. It’s always fun to glam up and show a different side of myself."

Although she doesn’t flash a lot of skin or have any hot love scenes in "American Wedding," she does get to say some eyebrow-raising dirty talk to co-star Eugene Levy. In this event, her dialogue could qualify as the "something blue."

Innocent joke Her bottom-lip nibbling character of Michelle Flaherty always had a buried sexual aggression that used her innocent appearance as part of the joke.

In the first "American Pie" movie, Jim (Jason Biggs) settles on her because he struck out with his dream girl. After listening to Michelle’s insufferable sing-songy "This one time ... at band-camp ..." stories all night, she stuns him by describing an erotic use for her flute — then smacks him around during rough sex as she eradicates his virginity.

Jason Biggs, left, and Hannigan in "American Wedding." "All of her lines had a question mark at the end of them. I sort of just fooled around with it for a few minutes, and just immediately heard her voice," Hannigan said. "And of course now it will never leave my head.

"I definitely try to avoid any similarities in our speaking," she added. "I can never start a story with ’This one time ...’ Those words have sort of been nixed from my vocabulary."

Even Willow, who started out on "Buffy" as the brown-jumper-wearing shy schoolgirl — good with computers and occult research, bad with boys and fashion — eventually absorbed Hannigan’s subversive sensuality, said series creator Joss Whedon, who described the actress as "one of my favorite people in the universe."

"As characters evolve they become more like the actor playing them," he said. "So Willow started getting sexier and cooler and more empowered. Alyson is too cool and sexy to remain nerd-girl for too long."

The character evolved to a powerful good witch, discovered her lesbian sexuality and (after her lover was killed in the sixth season) became a wicked humanity-hating sorceress before switching back again to a lovable best friend.

"I think she’s grown more than any character, but she had so much room to grow," Hannigan said in an earlier interview on her last day of filming for the "Buffy" finale in April.

Hiding in the shade of a trailer to keep the sun off her makeup — a flowing white wig and pale eyebrows for a special-effects scene in which magic temporarily washes out her red locks — she said the key to the character was unrelenting optimism.

Hannigan says her real-life wedding will not be anything like the traditional ceremony depicted in "American Wedding." "She was sort of happy, even if she was talking about something sad," Hannigan said. "That’s sort of where I found her."

Real-life wedding Her work on "American Wedding" came as she was planning her real-life wedding to Alexis Denisof, who plays the awkward, British demon-hunter Wesley Wyndam-Pryce on the WB’s "Buffy" spin-off "Angel." The nuptials are set for the end of this year.

The two fell for each other when he did a temporary stint on "Buffy" in 1999. "It was basically instant flirtation," Hannigan said, once again negotiating her car through the Hollywood traffic. "But he didn’t want to date somebody he was working with. But we became immediate friends and flirted with each other shamelessly.

"I mean," she added, "it was pretty obnoxious."

Her real wedding won’t be anything like the showy, traditional ceremony in "American Wedding."

"Ours won’t be black tie and it’s going to be smaller. It’s going to be really, really fun and just sort of express who we are in our relationship," said Hannigan. "I find myself explaining to my family what’s happening. I’m like: I know you hear ’wedding’ and have all these sorts of ideas, but you can just scratch that."

She grew up in Atlanta and started her career as a child, modeling for her photographer parents. She said she always prodded her father to be "funny" and learned that "a good way of getting out of trouble was making my mom laugh."

After working in TV commercials, she was 14 when her first movie debuted: the 1988 family comedy "My Stepmother Is an Alien," with Dan Aykroyd and Kim Basinger. Later she had small roles in 2000’s "Boys and Girls" and 1998’s "Dead Man on Campus."

Now that she has reached leading lady status, Hannigan said she hopes the goofy comedy parts don’t go away.

"If a great part comes along and it’s not the glamour-puss, then it’s not like I’m not going to do it just because I don’t get to wear the best clothes and stuff," she said. "I’d much rather be funny than sexy.

"I mean ..." she hesitated. "It’s great if I can do both."