SANTA MONICA, California – On a chilly January weekend in Los Angeles, I turned into a truffle pig. I foraged relentlessly all over town, looking for truffle fries.

By Monday, when it was time to go to my interview, the only thing in my suitcase I could squeeze into was a Spanx dress.

“My sister gave me this for Christmas,” I explained sheepishly to the famously lissome Calista Flockhart as I slid into a booth on the terrace of the Georgian Hotel. “I guess you’ve never owned any Spanx.”

“I love Spanx,” she said. “In fact, I just ordered – no kidding – a pair of Spanx jeans. They make really cute jeans. They’re very wide.”

Seeing my sceptical look, she reminded me: “It’s not only about sucking it all in. It’s about smoothing it all the way. No panty lines.”

And then, as we sat in this romantic spot, looking out at the ocean, she said the thing that made me fall in love: “Would you like to nibble on something? How about some french fries?”

And, suddenly, I realised how much I had missed the woman who shot to mega-stardom in the late 1990s as Ally McBeal, the quirky Boston lawyer with miniskirts and maxi-neuroses – a role she reprised at the Emmy Awards in January, doing a whimsical dance with her male former co-stars on a set resembling the show’s fabled unisex bathroom, with Barry White on the soundtrack.

Flockhart virtually disappeared from stage and screen at the height of her stardom, riding off into the Brentwood sunset with another star, American actor Harrison Ford, 81. She had dropped out to be a mum, to focus on raising Liam, the baby son she had adopted a year before meeting Ford in 2002.

Now, at 59, she is back, playing a bouffanted Lee Radziwill in American writer-director-producer Ryan Murphy’s Feud: Capote Vs The Swans, the second season of his anthology series now available on Disney+ and which Murphy has described as “the original Real Housewives”.

For 30 pieces of silver and to satisfy his literary ambitions, acclaimed American writer Truman Capote (played by Tom Hollander) turned on his beloved swans, the willowy socialites who reigned over New York society in the 1950s and 1960s.

He revealed their seamy Upper East Side secrets – from adultery to alleged murder – in a 1975 Esquire article, La Cote Basque, 1965. In it, he referred to Radziwill and her sister, Jackie Kennedy, as “a pair of Western geisha girls”.

Five decades later, Flockhart joins a flock of big-name actresses on Feud.

Naomi Watts plays the No. 1 swan, a tortured Babe Paley, who was considered by Capote to be the most perfect woman ever made; Diane Lane is Slim Keith, who pushes to ostracise the Judas writer; Chloe Sevigny is the society doyenne C.Z. Guest; Molly Ringwald is sweet West Coast swan Joanne Carson; and Demi Moore is Ann Woodward, a showgirl who shot her banking-heir husband to death, but was never charged because she claimed she had mistaken him for a burglar.

Murphy, 58, said that Flockhart had always been at the top of his list to play Radziwill because he had heard tales of her brilliant stage performances as a young woman.

“Lee Radziwill was, of all of them, the most viperous and the darkest, the most in pain,” he said. “She was the most famous – American royalty.

“I wasn’t sure that Calista, who had been Ally McBeal and really had a reputation of being America’s sweetheart, girl next door, would want to do something like that at this point in her life. But she said yes with no hesitation. She really went for it, which I admired. She was sharp and dagger-like.”

Although Jackie Kennedy is featured in only one scene in Feud, Flockhart said she had read up on Radziwill’s competitive relationship with her older sister.

“Truman Capote recognised that she was living in her sister’s shadow,” the actress said, “and he would say things: ‘You’re so much prettier. You’re so much smarter. You’re more interesting. You have better style.’ She really needed to hear that. I think it made her really love Truman. He was fun, and she confided in him, like they all did.”

I worried at the time that several of the actresses in Ally McBeal creator David E. Kelley’s universe – Flockhart, Lara Flynn Boyle, Courtney Thorne-Smith and Portia de Rossi – were getting too thin. Thorne-Smith and de Rossi later talked about their 300-calorie-a-day eating disorders.

Flockhart said she had been hurt by chatter about whether she had anorexia.

“I don’t think that would ever happen today,” she said. “They call it body-shaming now. I haven’t thought about it in a long time, but it’s really not okay to accuse someone of having a disease that a lot of people struggle with.

“It wasn’t the case, and there was nothing I could do to convince anybody or get out of it. If I had worn a big padded bra, they probably would never have been able to target me in that way. I look back at pictures, and I’m the same then as I am now, and nobody says a word now.

“I was an easy target, I guess. It was painful, it was complicated. I loved working on Ally McBeal, and it just made it sour. I was very sleep-deprived and I was depressed about it. I did think that it was going to ruin my career. I didn’t think anybody would ever hire me again, because they would just assume I had anorexia, and that would be the end of that.”

“Clearly,” she continued, “I had days where I was really hurt, embarrassed and infuriated. I was lucky that I had to work. I just put my head down. I always felt like, ‘Calista, you’re a good person, you’re not mean to anybody’, and I’m confident in that.”

She added: “I honestly have never been in a situation where I have to watch my weight. My mum is 4-11 (1.5m) now, and she weighed 93 pounds (42kg) when she was married. Talk about a little tiny elf. I just have small bones, and I just am lucky.”

Asked about the talk of an Ally McBeal revival, she said: “I would definitely consider it.”

Luck has been on Flockhart’s side too when it comes to her marriage – she and Ford wed in 2010 – as the celebrity couple seem to have maintained a romantic and playful relationship.

She mused that one of the reasons that it has worked is because she was “really content being home” as a full-time mum. “I didn’t have the same dreams at the time, so we weren’t competing with each other.”

And Flockhart was not daunted by the 22-year age gap. She said she often feels like the older one, adding drolly, “because he’s so immature”.

“I think he was a really good father in a lot of ways, and maybe because he was on Round 2 or Round 3, so he had matured and grown up and, I think, evolved into being a good father,” she said. “He’s such a good father to his kids now. I love his kids, my stepkids.”

“We’ve had to work,” she said about her marriage. “We’ve had our ups, we’ve had downs like everybody else – mostly ups, which is good – and we just stay together. He’s the person that I want to call when something happens. That knee-jerk thing where I have to call Harrison.” NYTIMES

• Feud: Capote Vs The Swans is available on Disney+.