When Stéphane Louvard decided one day to cross a croissant with a chocolate chip cookie “for fun” he had no idea it would turn into a global gastronomic phenomenon.

Now, he has found his Parisian boulangerie besieged by pastry lovers in search of “le crookie”, after his creation was taken up by a string of social influencers on TikTok

“It’s totally insane,” he told The Telegraph as his team prepared another huge batch of the high-calorie pastries in kitchens under his boulangerie Maison Louvard in Paris’s eastern 9th arrondissement.

“I was happy with my croissants that day back in 2022 and saw my young team making cookies and thought let’s have some fun.”

At first, he sold a few dozen a day to regulars at best.

Interest picked up after a video posted by the Instagram account “The Ultimate Guide”, which specialises in Paris’s restaurants, driving sales up to 150-200 per day.

But the real catalyst was a post in January by Johan Papz, a French TikToker who filmed himself tucking into one and exclaimed: “C’est une dinguerie” (It’s crazy good).

Three million views later, the bakery was taken by storm with influencers in Britain, America and elsewhere fanning the frenzy.

“It took a day or two, then the queues started. From 150, it went up to 400, 500 then 1,600 and often over 2,000 a day,” said the bemused 51-year-old, who had to take on two extra workers to meet the demand.

“I met a Spaniard who had come all the way from Madrid just to try one,” he said.

“We couldn’t keep up. I thought it would die down after a week, but no. That’s the thing with TikTok. One video spawns dozens more.”

“We used around 25kg of flour for croissants before. Now it’s around 70kg just for the croissants.”

His wife Virgine, 47, said: “We’re delighted but it was like a bomb going off overnight. Social media is crazy in that when influencers tell people to go and try something, they do it – a bit like sheep.”

“We get criticism - it’s too expensive (€5.9 to takeaway and €7.10 to eat in situ) but it’s the price of a croissant and cookie separately plus 50 centimes for the extra work,” she said.

The original crookie has spawned a plethora of imitations in rival bakeries and frozen goods chain Picard but many visitors were curious to taste the original as they queued for the pastry this week.

Londoner Adam Sandford, 31, tucked into one outside the shop on Sunday without the slightest hint of guilt, having just completed the Paris marathon.

“I like this. It works. I love a croissant but if I can have a cookie as well, why not?” he said. He had no problem with the fact that he had found the place thanks to social media.

“I didn’t know about this place and it’s put them on the map. It’s just a bit of fun,” he said.

In the queue, German teenager Mia Czwallina, 17, said: “They’re already imitating it in Frankfurt but I wanted to try the original.”

A group of Brazilian exchange students in their early twenties were ecstatic. “It’s all over Brazil,” said Ana Marinho, 21, from Rio da Janeiro and studying in Bordeaux.

Newlywed American couple John and Kelsey Healy, both 23 and from Cape Cod, Boston, had made a detour after spotting the pastry on TikTok during their whirlwind Europe honeymoon. They had just spent three days in London.

“It’s very sweet but very good. It’s something new. Our French tour guide seemed appalled at the idea but we wanted to give it a go.”

Mr Louvard denied it was sacrilegious to adulterate the classic croissant beurre, officially dubbed a viennoiserie as its origins are Viennese.

Beyond the “pain au chocolat”, this is by no means the first time the croissant has been morphed into a new portmanteau pastry, he said.

In 2013, New Yorkers couldn’t get enough of Dominique Ansel’s cronut - half-croissant, half-donut. Then in 2022, the New York Roll, a mixture of croissant and bombolone (an Italian pastry) went viral, with videos featuring the cake accumulating hundreds of millions of views on TikTok.

But Mr Louvard said the quality of the croissant remains key. “It only works because the croissant is a proper crusty homemade one,” he insisted.

It is then left to cool, cut open and cookie dough is inserted with more placed on top. It is then rebaked until the outer dough becomes crusty and the inside melts.

A crucial ingredient, Mr Louvard explained, was the richly aromatic Mayan Red chocolate used by a producer in Costa Rica, who, he said, cultivates cacao of a single varietal “like grapevines”. It is roasted for half the time of industry standard and at a temperature 20 per cent lower, removing any bitterness.

“Just don’t eat them every day. They are a little rich,” confessed Mrs Louvard, tucking into a healthy falafel.

Compared with its weighty rival, the simple croissant beurre – far superior to the croissant ordinaire made with margarine – offers an (admittedly illusory) light and flakey feel thanks to a technique called lamination, which sees a yeasted dough thrice “turned” or folded around sheets of butter, creating 27 layers of butter encased in 28 layers of dough.

Call me old-fashioned but this correspondent can safely say I prefer the good old croissant beurre. I’m frankly no fan of cookies (or TikTok for that matter) and a croissant is enough cholesterol already.

The queues at Maison Louvard suggest others disagree. But that’s the way the crookie crumbles.