It's choux time: Move over, cupcakes - éclairs are having a makeover

The latest versions are colourful, crammed with custard, and set to take over our teatimes.

They originated in France in the 19th century and the feather-light choux pastries covered in chocolate and filled with a puff of cream have always been a popular teatime treat. But now éclairs are undergoing something of a reinvention. With help from stores including Selfridges and Marks & Spencer, restaurants such as Fifteen and Yauatcha and cookbooks such as Secrets of Éclairs by Marianne Magnier-Moreno, sales of this pastry are up 23 per cent this year.

"It's the new cupcake," declares patissier Eric Rousseau, whose éclairs are sold both in Selfridges London's afternoon tea venue Dollies and in his own patisserie in Stoke Newington, London. "It's really popular. It's here to stay."

The extensive éclairs line at Selfridges was released earlier this summer and has proven to be a tremendous success. "The thing that's really surprised me is that the new flavours have actually overtaken the chocolate éclair," Selfridges bakery buyer Nicola Simons says. "It's quite incredible how well they've done." Rousseau's line at Selfridges includes 12 varieties such as strawberries and cream, peanut butter, salted caramel and marshmallow – all of them so colourful and decorative that they make the most ornate modern cupcake look rather staid in comparison.

Though he does not have plans to create savoury version any time soon, Rousseau says you don't have to limit yourself to éclairs with just sweet ingredients. You can create éclairs that are salty and even, he says, with a hot-dog filling rather than a cream filling. "It's so versatile," he says. "You can garnish them from any angle, any flavour and any texture. You can really play with them. It's so easy to change things around."

Standing in Rousseau's kitchen about a 10-minute drive from Belle Epoque, his patisserie, I learn how to make his mango and jasmine éclairs. His eclairs are filled not with cream but with an exotic custard mixture, in the French style. The chocolate-iced, cream-filled version is an English variation. But the choux pastry is common to both and needs to be right – light and airy and slightly crisp. The high water content helps to puff it up during cooking to get that open profiterole texture. Flour is stirred into a mixture of butter and water, then stirred to form a ball of dough. Eggs are then stirred in to make a gooey paste.

The dough ready, my first task is to pipe it onto baking paper. What sounds like a simple process proves difficult. At first, my éclairs are too thin. And then they aren't thin enough. "You have to make it perfect or we cannot sell it," Rousseau says as he scrapes my attempts off the pan.

Finally, I get the éclairs just the right size and Rousseau is satisfied enough to move on to the next stage, which is buttering the éclairs and putting them in the oven. As the éclairs bake, I learn how to make the fillings, including chopping up the mangos into perfect circles and whipping the cream, and tasting as I go.

The jasmine filling is phenomenal and delicious on its own. I can't wait to taste it in an éclair with the mangos. "It's just two to three drops of jasmine, no more," Rousseau says. "It adds the perfect flavour."

The éclairs are finished in the oven and an incredible smell wafts through the kitchen. The fun of decorating and filling begins, and, aside from the ones I take home to enjoy, the éclairs I create are to be sold at Selfridges the next day.

This summer, Marks & Spencer also picked up on the éclair trend with flavours such as triple chocolate, and white chocolate and raspberry. "Our éclairs have done very, very well" M&S product developer James Campbell says. "We've had a lot of positive feedback."

The store's Christmas dessert line will include salted caramel and dark chocolate truffle mini éclairs. "With our mini size, it's perfect and you don't have to feel guilty," says M&S desserts buyer Carrie Johnson.

Though available in a wider selection in the above stores, éclairs are also becoming a popular dessert in upscale London restaurants such as Yauatcha and Jamie Oliver's Fifteen. A Michelin-starred dim sum restaurant in Soho, Yauatcha is also known for its delicious pastries. On its dessert menu is a strawberries and cream, and a chocolate and hazelnut praline éclair.

Yauatcha's executive pastry chef, Graham Hornigold, decides his dessert flavours based on both the seasonality of the ingredients and various events that are occurring around London. The strawberries-and-cream éclair is part of a line of Wimbledon-themed desserts served at the restaurant this month. Hornigold loves the versatility of éclairs. "You name a dish, and I'll try to make some sort of cake for it," he says. "It's up to your own imagination and your ideas to make a traditional dessert like an éclair unique."

A strawberries-and-cream flavoured éclair, an obvious favourite this summer, is also making an appearance on the menu of Jamie Oliver's Fifteen restaurant, along with a chocolate mousse flavour. Head chef Jon Rotheram says these éclairs are among his most popular desserts. "Everyone's asked for them. It's nice. I think people are really embracing it – it's a really trendy thing," he says.

Could éclairs be just that, a fad that disappears quickly? Chefs and buyers don't think so. "I don't see them fading out," Rotheram says. "They've been around for so many years. It's a classic and classics don't go away. I hope it continues because I think they're delicious."

Of course, the trend for éclairs extends beyond these shores, too. In Paris, they reach a sort of apotheosis. At Le Meurice Hotel on the Rue de Rivoli, the pastry chef Cédric Grolet makes an éclair constructed entirely of chocolate and another of rhubarb and strawberry, which looks like some sort of modernist sculpture.

Whether you buy the dessert at Selfridges or Marks & Spencer, consume it in Paris or at Yauatcha or Fifteen, or even make your own with the recipe above, it's a fad that could soon make cupcakes look rather passé.

Eric Rousseau's Eclairs

250ml milk
250ml water
5g salt
10g sugar
220g unsalted butter
280g flour
8-9 eggs

Put the milk, water, salt, sugar and butter in a pan to boil. When boiling, add the flour, stir well and cook for 3-4 minutes. Take the ingredients off the heat. Place the mixture in a bowl and add the eggs two at a time. Mix well. Pipe using a No20 nozzle onto baking paper so the eclairs are 12cm long. Brush with melted butter and use the back of a fork to mark the pastry lengthways. Bake for 30 minutes at 170°C.

Rose water mousseline filling

500ml milk
125g sugar
50g flour
25g custard powder
3 eggs
1 vanilla pod
200g unsalted butter, cubed
Rose water essence
Raspberries and chocolate

Cut the vanilla pod in half, and take the seeds out. Add the milk, bring to boil and let it rest for 30 min so that the milk is infused with vanilla. Add half the sugar to the milk. Bring back to the boil.

Whisk the rest of the sugar with the eggs until white and silky. Add the flour and custard powder and mix well. Pour one ladle full of boiling milk into the mixture. Mix well.

Transfer this mixture back into the other half of the boiling milk. Stir and simmer for 3 min. Keep stirring so that it doesn't burn.

Add 100g of butter to the hot cream. Pour into a container, cover with cling film and pop it into the fridge to cool.

After 30-60 min in the fridge (after the cream Patissier has cooled down) transfer to a bowl, add the remaining 100g of cubed soft butter and whisk with an electric hand mixer to create a silky cream. Add the rose essence, and mix well again. Bravo, you just finished a French mousseline cream. Put to one side.

When the eclairs are cold, slice the tops off. Crush a handful of raspberries in a bowl and spoon a thin layer to cover the bottom of each eclair.

Next, fill a piping bag with mousseline and pipe it into the eclairs until they are full. Smooth the surface.

Pipe five balls of mousseline onto the tops of the eclairs, and add a raspberry onto each dollop. Add chocolate shards or shavings. Voilà.