NEW YORK, NY.- On a round table in her dressing room at the Lunt-Fontanne Theater, Annaleigh Ashford always has a 1,000-piece puzzle in progress. The current one reveals a picture of a cat. Fellow cast members of “Sweeney Todd” slot in pieces as they come and go throughout the night, bringing coherence out of chaos, making a whole out of many parts. It is, Ashford said, “our little homage to Steve,” referring to Stephen Sondheim, the musical’s composer and a lover of puzzles and games.

On a recent Monday, her sole day off, Ashford had come to the Uncommons, a board game cafe in Manhattan’s West Village neighborhood, to find a new puzzle. She would assemble it while she discussed playing the musical’s Mrs. Lovett, a pie maker with a grisly approach to fillings. She arrived in a white short-sleeved, high-necked sweater, dotted with outsize ladybugs, and her affect was as wholesome, earnest and embraceably eccentric as her style. If she had worn a flower in her blond hair, I would have expected that flower to squirt.

The Uncommons had just a few puzzles on offer — an image from the game Exploding Kittens, a riff on “A Christmas Carol.” Then she saw one more, an 800-piece rectangle titled “Theater District.”

“Oh,” she said, “we have to.”

A Tony winner for a delirious turn in the 2014 revival of “You Can’t Take It With You” and a nominee in 2013 for a brash performance in “Kinky Boots,” Ashford, 37, has known her way around the theater district for a while. An actress of vulnerability and pizazz, with a voice built for the back row of the balcony, she often finds herself between shows on a Saturday saying a little prayer for the other actors on Broadway.

“Like, have a good show everybody,” she said. “God protect everyone as they take the journey today.”

No other journey has required as much of her as “Sweeney Todd,” a macabre illustration of a penny dreadful tale about a murderous barber and his accomplice, Mrs. Lovett, who repurposes his victims as her key ingredients. Ashford’s giddy parts, her wounded parts, the mother, the lover, the clown — these are all baked into her Mrs. Lovett, a portrayal that has earned her a Tony nomination for best leading actress in a musical.

“Everything goes into the work,” Thomas Kail, who directed this revival, said of his star.

That’s what Mrs. Lovett deserves. “She’s one of the great characters of the American musical theater canon, one of the best parts ever written,” Ashford said. She found a missing piece of the “Theater District” puzzle and clicked it into place, then sat back, satisfied. “How can you ever not love her?”

Ashford, who grew up in Denver, seems to have come out of the womb with her baby fingers doing jazz hands. A child of athletes, she had little physical prowess. So her mother instead signed her up for singing and acting and dance, which she took to with unusual seriousness.

“Even as a little person, it wasn’t about just being seen, it was about the telling of the story,” she said.

Upon graduating from high school at 16, she enrolled at Marymount Manhattan College — the only New York school that would take her. (She had known that she wanted to be a New Yorker ever since she saw the R-rated movie “All That Jazz” at the wildly inappropriate age of 8.) After completing her Bachelor of Fine Arts degree at 19, she spent the next three years going from audition to audition, but couldn’t land a single callback. Eventually, a part in an early version of “Next to Normal” materialized, as did a spot on a “Wicked” tour. Then Jerry Mitchell, the Broadway director and choreographer, saw her for “Legally Blonde.” She was auditioning for the role of Margot, the dizziest of the sorority sisters, a woman who has deep conversations with a Chihuahua.

“She was the only person who actually made me laugh,” Mitchell recalled, more than 15 years later. “Because I really believed she was talking to the dog.”

Mitchell had worried about her limitations as a dancer. But he found that given time she could master any step he threw at her. Any note, too. Most important, her instinct for comedy proved passionate and unerring.

Other roles came, several of them further variations on the dumb blonde: Glinda in “Wicked”; Essie in “You Can’t Take It With You,” her Tony-winning part; Sylvia in “Sylvia,” in which she played a blond dog. Television has often cast her this way, too. Most recently, as Gina, a kidney donor, in the Chuck Lorre sitcom “B Positive.” Lorre, in an email message, described her method as “a perfect mixture of mastery and joy.”

Ashford used to struggle, she said, “with playing girls who were not the smartest rock in the box.” She now plays a somewhat wider range of characters — shrewd blondes, guileless brunettes — and she struggles less. “Maybe I’m not in a box of rocks anymore,” she said brightly.

Her intelligence, of course, has never been in doubt. “Annaleigh is brilliant,” said Michael Greif, who cast her as Maureen in the post-Broadway run of “Rent.” “Part of the brilliance is how canny and sharp and original that mind is.” So original that she asked to wear udders during Maureen’s performance-art number, “Over the Moon.” (Greif said no.)

Yoked with that mind is a clarity of purpose, tinged with a belief in the divine, which can resemble a kind of innocence. Sarah Paulson, who worked with her on “Impeachment: American Crime Story” and filmed a movie with her last summer, described that clarity as lending Ashford a certain buoyancy.

“She can seem like she’s dancing in the ether a little bit,” Paulson said. But Ashford also has a seriousness to her, which Paulson described as “a fierce self-possession, this unassailable confidence that is wild to me.”

Ashford had her first taste of Sondheim as a child, via cassette tape. She can still remember hearing “Sweeney Todd” in elementary school and finding it so scary and so wild. With the exception of a benefit reading of “Assassins,” her first professional experience of Sondheim was in 2016, playing Dot, the artist’s model, in “Sunday in the Park With George.” Sondheim often attended rehearsals and would answer any questions.

“He gave the best notes,” she said. “They were all about making sure the audience heard and understood the story.”

So when the call came about Mrs. Lovett, a role that another one of her heroes, Angela Lansbury, had originated, she answered. Eager to work with Sondheim again, she moved her family back from Los Angeles. (She is married to actor Joe Tapper, and they have a young son.) She had many questions about the role, but she didn’t want to bother the composer. She would wait for the first reading, she decided. Sondheim died late in 2021, just days before that reading. It went on without him.

“We had to show up and do the work,” she said. “He would have wanted it, he would have loved that.”

Without Sondheim to advise her, she turned to the music, and the text and her colleagues.

Gradually she found a Mrs. Lovett who was younger than the usual iteration and needier. She wants Josh Groban’s Sweeney not only as a protector and a butcher, but also, and enthusiastically, as a lover and a husband. (“We always say that I climb on him like a tree,” Ashford said.)

Groban marveled at the creativity and seriousness with which she could craft jokes. He recalled watching her put together the number “The Worst Pies in London,” experimenting with the rolling pin, the flour, the ball of recalcitrant dough.

“There’s so much to play with, there’s so much to react to,” Groban said. “There’s so much that she gives and gives and gives.”

Ashford’s Lovett isn’t only a clown. Or rather her clowning comes from a place of real pain. Ashford can locate that anguish even in a manically silly song like “The Worst Pies in London.” Yet in the line “Times is hard, sir,” she lets the wound beneath the lyric come through.

“He gives you these little clues,” Ashford said of Sondheim. “Because it’s a puzzle.”

For the answers to other clues, she often has imagined conversations with Sondheim. “I ask for help getting through the puzzles for the night,” she said, the puzzles of how to unlock a character’s motivation, how to land a joke. “Usually we find an answer. Or at least a version of the answer.”

After an hour and a half at the Uncommons, the border of “Theater District” was very nearly complete. A few pieces were missing. It didn’t matter. Because Ashford has already solved the more important puzzle: how to take all the wounds and sparkle and joy and pour them into this part.

“I have to be an artist,” she said, tipping pieces back into the box. “There’s nothing else I could ever do. Thank God, it’s worked out.”

This article originally appeared in The New York Times.