It takes a considerable amount of French swagger to turn up in London and rebrand afternoon tea, but if anyone can do it, Cédric Grolet is the man. Grolet is one of the greatest patissiers currently walking the Earth. I say one of, because the maker of the world’s most exquisite Paris-Brest or best mille-feuille is a highly contestable matter, but Grolet is definitely in the frame.

Having started out at the age of 11 in the kitchen of his grandparents’ hotel in the Loire valley, Grolet was winning awards for sugar art by 15, before going on to work at Fauchon and Le Meurice, both in Paris. This diminutive, sugar-fuelled powerhouse was soon taking on the globe with his increasingly famous trompe-l’oeil artistry. I’ll translate: his specialities include a lemon cake that resembles a lemon and a hazelnut tart that looks remarkably like a hazelnut. He was deemed best head patissier in France in 2015, 2016 and 2017, and a year later won the title of the world’s best pastry chef at the 50 Best awards.

Grolet’s bid to spike the blood sugar levels of metropolitan Europe has seen him open a sort-of cafe, sort-of cake laboratory in Knightsbridge, and serve not strictly afternoon tea, but “gouter”, or taster. He has always felt that his work is at its very best seconds after all the piping, spinning, spraying and tweezering finishes, so now customers can sit up and enjoy viennoiseries, cookies and a few savoury items at the counter in this starkly pretty, Rémi Tessier-designed lab area full of white marble, polished stainless steel, shiny, scallop floor tiles and walls carved with flowers and lemons. Or you can sit in a more hotel-lobby-feeling, cushioned area for the gouter menu, for which the tea is served in black cups with no handles, because, well, we’re not in Betty’s tea rooms any more.

Obviously, the French would never do anything as gauche or wantonly pleasurable as sit down at 3pm with a heaving cake stand of egg-and-cress finger sandwiches, fairy cakes and trifle, before eating until they’re edging on bilious. Instead, Grolet’s afternoon tea dances with the French idea of bridging the gap between a fine lunch and a proper dinner with a series of small, yet meaningful sweet tastes, just as French parents do for small children. Grolet’s gouter menu, a snip at £90, including tea or coffee, takes place in the Berkeley hotel and features five mini-versions of his classic creations: petite hazelnut, petite lemon, petite Paris-Brest flower, a vanilla flower and his take on the British scone.

A Frenchman wading into the UK’s fractious “jam or cream first?” scone debate is either foolhardy or admirable, but Grolet has form. Back in 2017, he released a recipe for scones with a crumble topping, seemingly believing that crunchy scones were something Britain lacked. He may as well have gone to the Tower of London and shooed off the ravens, although I can’t help but sigh at his panache. These days, Grolet’s “scone” has an added layer of marmalade and the toppings are baked within, giving it a similar shape and vibe, but not taste, to a Mr Kipling fondant fancy. Grolet is currently on hand in his new Knightsbridge cafe to explain and justify his techniques, which meant that, on the day I visited, the place was bedlam, with him meeting and greeting a queue of customers snaking down the road all urgently needing to part with £25 for a single full-sized vanilla flower cake.

At this point, you might ask: “But how can a cake cost this much, when a Greggs yum yum is about 85p and delivers a satisfying whack of pillowy doughnut without any need to remortgage the house?” This is where Grolet’s laboratory comes into its own, because you can watch him take a wafer-thin pastry case, fill it with a delicate layer of pale vanilla ganache, load in a disc of light, vanilla-scented sponge, brush it lovingly with glossy huile vanille, pipe in the best praline I will ever taste, then leave it all to set, before icing it with mousse vanille in ornate, perfect, concentric petals and creating something that’s almost too beautiful to push down one’s throat. It is impossible to begrudge Grolet his money for this experience.

There’s a wonderful video floating around the internet right now in which crafters, designers and artists post videos of the laborious process behind their magical finished products, all accompanied by a chipper song with the lyrics, “It costs that much ’cause it takes me fucking hours! It costs that much ’cause I don’t have superpowers”, and this is very much the case here. Grolet’s souffle, waffle flower and marble flower cake cost 25 quid a pop because they’re not made by machine, or by invisible pixies, but by living, breathing technicians who take spreading marmalade on a scone as seriously as building a Formula One car.

Grolet has arrived in London, shaken up afternoon tea and convinced me that £90 is a perfectly reasonable price for five small tarts and a glass of Laurent-Perrier, before sending me off so giddy on praline and huile vanille that I immediately booked his £135 “chef’s choice” tasting menu experience. Grolet is outrageous on many levels, but he does it so very sweetly.

• Cédric Grolet at the Berkeley Wilton Place, London SW1. Open all week, 8am-6pm. Pastries from £5 to takeaway; eat-in menu from £20; five-course “gouter” menu £90; seven-course “chef’s choice” menu £135, all plus drinks and service