When you think of Hollywood A-listers’ snacking habits, bread, butter and potato chips might not be the first things that come to mind.

But for “A Big Bold Beautiful Journey” co-stars Colin Farrell and Margot Robbie, that’s what makes up snack they bonded over on the set of their romantic fantasy film.

On Sept. 16, Farrell and Robbie appeared on TODAY and introduced Craig Melvin to an across-the-pond delicacy that piles carbs on carbs.

“I understand that you, also, during the course of the filming, you would send her a gift to make up every day,” Craig said to Farrell before the actor corrected the anchor — he would “deliver” it. “What was this thing you were delivering?”

“So, she loves snack,” Farrell explained.

“Even when I’m not pregnant, I love to snack,” Robbie added.

“She’s constantly got pregnant appetite for the last 30-odd years,” Farrell joked, adding that during prep for filming, they discussed food.

“We had a rehearsal period, rehearsed for like two weeks before … a lot of that was just banter, just talking about our past, and I was talking about crisp sandwiches, which she calls ‘chippy sandwiches,’” Farrell said.

Crisp Sandwich Close-Up
A crisp sandwich. ClarkandCompany / Getty Images

“Tayto Cheese and Onion, white bread — white cheap bread — thick butter,” Farrell continued, mentioning Ireland’s premiere crisp brand. “I brought one in for her every morning, that was my job.”

“Heaven,” Robbie noted.

Of course, Craig wanted Robbie and Farrell to “feel at home” while on the show, so he brought out three freshly made crisp sandwiches to genuine excitement.

As Farrell said the sandwiches look “very good,” he had to do one thing to complete them to his liking.

“I can tell you one thing we messed up at the start,” he said, grabbing a sandwich and then pressing all of his weight into it to flatten it, making a loud crunch.

“Margot, this is yours, of course,” Farrell told her.

“I haven’t had breakfast yet,” Robbie said, taking a bite. “This is perfect.”

“Is that Tayto?” Farrell said with surprise at the sandwich’s accuracy. It was so accurate, in fact, it drove the movie star to curse live on-air.

“I f—ing knew it!” Farrell exclaimed to shock and laughter from Robbie and Craig.

Though they may seem unusual to the unfamiliar, crisp sandwiches are a staple food in the UK and Ireland. Though the origin of the recipe is up for debate, they’re said to have been created in the 1960s. Since then, they’ve become so widespread that Nigella Lawson has shared her adoration — and her own recipe — for the snack on social media.

And in a recent viral video on TikTok, one woman’s Irish fiancé taught her the “delicacy” of a crisp sandwich at 4 a.m. after an Irish wedding.

When she notes that he doesn’t toast the bread, he gives her a horrified look and says, “Toasting a crisp sandwich is crazy.”

He then presses down on the sandwich, delivering the most satisfying crunch.

“That means you know it’s good,” he says.