I’m in Lisbon listening to some live fado, the Portuguese folk music that expresses the sorrows and yearnings of ordinary people. Among these songs of love and loss is a hymn to the joys of Pastéis de Belém, the original version of the most traditional cake in Portugal, the pastel de nata, or custard tart. “Served with cinnamon or just as it is,” sings the lyricist Leonel Moura, “This beautiful delicacy has no equal in the world.”

It’s hard to imagine the British custard tart inspiring such passion. You can find the Portuguese version across the UK of course, but I wondered if we had a worthy home-grown opponent. I couldn’t find any in my local independents. Not even Greggs, the biggest baker in the country, stocks the British custard tart.

In Portugal, pasteis are found on every street corner. Their home, however, is the bakery in Lisbon’s Belém district, which bears the name of the tart immortalised in the fado song. Pastéis de Belém, a family-owned business, has been making the tarts since 1837 and serves up to 50,000 a day in peak season. These are reputed to be the world’s best. They are distinguished from other pastéis de nata by their slightly salty and extremely crisp puff pastry – partly from being baked at 400C – and the custard, made only with milk, not cream, which is less sweet. “Here in Portugal, almost every traditional cake we have was invented by a monk,” manager Miguel Clarinha tells me. One such brother, from the Mosteiro dos Jerónimos in Belém, sold the recipe for their tarts after the monasteries were closed by the state in 1834. The buyer started making the cakes and they haven’t stopped baking since.

Lisboa Patisserie in west London, which opened in 1995 and claims to be the first Portuguese pastelaria in London, is just one of the several bakeries that helped popularise pastéis de nata in Britain. There are now many fine UK examples, but those at Portuguese Taste, a modest stall in Bristol’s St Nicholas’s Market, are declared superior to those in Belém by many expats. Owner and cook Maria Papanca’s pastry is light and crisp and her filling beautifully smooth. She too has a secret, which “is the way you make the cream – this I don’t tell anybody”. Yet, surprisingly, she achieves her excellent results using bought puff pastry, the only way to make production practical in her small market space.

In this custard tart fight, the British are taking a pasting. Yet ours have survived through the ages, too. According to the EU’s inventory of national foods, they originated in East Anglia and versions were made as early as medieval times. British tarts use the less flavoursome shortcrust pastry, which doesn’t provide as much textural contrast with the smooth custard. They are also topped with nutmeg, which fails to bring the custard alive as Portugal’s cinnamon does. Worse, they are now almost all mass-produced with palm oil-based pastry.

Chef Marcus Wareing has gone some way to reviving the English classic, with a recipe for an egg-enriched pastry, similar to a French pâte sucrée. But the best I’ve had are made by Laura Hart in her bakery under the arches at Bristol Temple Meads station. She too has her secrets but her basic formula is not complicated. She uses a puff pastry, with a cinnamon dusting rolled in at the end. Unlike a traditional English tart, cooked gently, hers are blasted at 200C, making the custard boil. The result is a wonderfully smooth, creamy filling with a slightly burned top similar to the Portuguese varieties, and a good crisp case.

So who would win a custard tart fight? If it were a team sport, the Portuguese would thrash us. But in a one-on-one, I’d back Laura Hart to defeat all-comers. This is one contest, however, you’d be well advised to judge for yourself.