My Big Fat Greek Wedding writer Nia Vardalos: I had 300 wedding guests on my side, my husband had eight

Centred around the Portokalos family, the movie saw 30-year-old Toula — deemed an old maid by her parents — fall in love with Ian, a teacher who is most definitely not Greek.

And it was another real-life familial moment that inspired Vardalos to write the Tom Hanks-produced sequel over a decade later, in which couple Toula and her husband Ian are embroiled in another round of chaotic family nuptials — except this time, it's Toula's parents who get hitched after they discover they're not legally married.

"My mum came to the set of my second movie Connie and Carla and she had made food for the whole cast including mini bun cakes with little flowers sticking out of each one," laughs Vardalos. In the film there's a moment of similar goodhearted familial excess in which the entire family of aunts, uncles, grandparents and cousins turn up en masse to Toula's daughter's university open day.

And as well as those tricky foibles of culture, family and romance, both Greek Wedding films look at the challenges faced by women everywhere. What does it mean to be a wife or a mother in a world with so many pressures and conflicting messages? Vardalos is emphatic that we need more films about this — but she adds that women will have to write them.

"Nobody’s going to tell our stories for us, we have to tell them," she says. "People say I'm a female screenwriter and I say ‘my vagina didn’t write my screenplays, I'm a screenwriter.' At the same time there's such an unemployed amount of females that have stories to tell in Hollywood and here [in Britain]. In that way I do celebrate my gender. We have so many things we are dealing with all the time."

Vardalos is in awe of Sharon Horgan, co-writer and star of Channel 4 relationship comedy Catastrophe, who she thinks hits the nail on the head when it comes to showing gender and romance on-screen.

"Oh my gosh, Sharon Hogran is amazing. Catastrophe is the anti-romantic comedy romantic-comedy. Her relationships are fantastic. It seems untouched by studio fingers.

"I think the goal is parity – I try to be pro-woman without being anti-man, and I hope and wish that men could do the same in that when they look at the screenplay they say ‘wait, wait, wait, is my daughter represented here, is my wife represented here? Is my sister represented?' Because the men didn’t come out of a penis, they came out of a womb so how can it be that men are not writing for women?"

This is the only interview I've conducted where the words "vagina", "penis" and "womb" have all been spoken in the same ten minutes. It's rather liberating.

And Vardalos is unusually friendly and eager to chat compared to most interviewees who have spent the day talking to press at a movie junket. She sits cross-legged in the hotel suite admiring the decor before complimenting me on my book of scribbled notes. “By the way I love how organised you are. I'm annoyingly organised. Your notebook — I'm like, we could be friends!”

This maternal warmth is no surprise, given that Vardalos has been open about adopting a three-year-old girl through the California Foster Care system, even writing a book Instant Mom about the experience. Her struggle to have a baby naturally was a huge part of the reason that we didn't get a Greek Wedding sequel much sooner. The new film is as much about Toula's relationship with her daughter as it is about white dresses. "It was a sad situation in which I was hiding that I was trying to become a mum – and it was really difficult for me. I didn't want to write about being a mother when I couldn't be a mother.

"Then all of a sudden I become a mum and was more grateful than I would have been if it had happened easily."

So how did the Big Fat Greek Wedding cast react when over a decade after their little movie blasted the box office, Vardalos told them she wanted to get the band back together for round two?

"Lainie Kazan [who played Toula's mother Maria] was the most keen. The cast definitely wanted the sequel and getting to make that call years later and say I've written it and we’re shooting in the spring. Everyone was on board immediately.

"John [Corbett, who plays Ian] was worried, saying 'we have this elderly cast, will they be ok?' Day one of the shoot we saw them party and laughing and John and I were like, we should just worry about ourselves..."

And the prospect of a third My Big Fat Greek Wedding is already on the top table. "I know an idea came to me during making the second," she smiles, keen not to give it away. "I haven’t started writing. But discussions have started and I’ve had the offer."

But despite the prospect of a third instalment in this smash-hit franchise, Vardalos says she still can't quite fathom how well the first film did back in 2002.

"It's bizarre to me because I thought I wrote a little movie about my family. I was shocked. I still am."

My Big Fat Greek Wedding 2 is released in UK cinemas on 25th March 2016