The chocolate fudge cake from Lana Cake Shop in leafy Greenwood Avenue has been in the spotlight since its owner, Mrs Violet Kwan, 88, announced that she intends to retire and wants to sell her business.

Over five decades, the shop has become something of an institution and although it sells an array of cakes, the chocolate fudge one is the most popular.

Generations of Singaporeans have celebrated special occasions and milestones with the rectangular blocks of chocolate cake covered in glossy frosting. Say the words "Lana Cake" and most people will immediately think of that cake.

It has special meaning for housewife Yip Wai Kuan, 52.

She ordered a 3kg chocolate fudge cake for her 21st birthday party, as it was "the go-to place for cake". She hopes to continue this tradition when her sons, now 19 and 14, celebrate their 21st birthdays.

"I am a stickler for tradition," she says. "Lana's chocolate fudge cakes are down to earth and old fashioned and I hope to share this connection with my sons."

Chef Anthony Yeoh, 35, of French restaurant Cocotte in Little India, says the cake was his "default birthday cake" if his grandmother did not bake him one.

Fuelled by nostalgia, he tried to "reverse engineer" the cake three years ago.

"The cake is soft and moist, and not crumbly, while the smooth frosting is not too sweet. I can't figure out the unique, magical charm of the cake," he says.

Others have also tried to replicate the cake and The Sunday Times finds at least nine shops which offer chocolate fudge cake.

Some owners say they were inspired by Lana to start their businesses.

Ms Jane Lim, who is in her late 50s and is owner of Jane's Cake Station in Jalan Kayu, says her interest in baking chocolate fudge cakes was piqued after she tried those baked by Mrs Kwan in the early 1970s. She says: "I tried asking for the recipe and this motivated me to bake a cake that could be as good as hers."

After "years of trial and error", and feeding her unsuccessful bakes to chickens that her family reared, she perfected her recipe and started her shop in 1995.

"I am still improving the recipe as I want to create a more rich and chocolatey flavour for the fudge by using Belgian chocolate, without it being too greasy and rich," she says.

Another stalwart is Vicky's Cakes in Bukit Timah Road. It was started in 1982 by Ms Vicky Tan, 71.

She says: "The chocolate used in the fudge and base sponge is bespoke to us, as we blend it to our specifications and we make a lot of effort to keep the sponge moist, tender and light."

Some owners started selling chocolate fudge cakes because they love chocolate.

Ms Lyn Lee, 42, owner of the Awfully Chocolate chain, which has more than 40 outlets here and in China, says she ate only chocolate desserts until she was 21. These included several birthday cakes from Lana Cake Shop.

She says: "I grew up in the west of Singapore and anyone who loves chocolate should know about Mrs Kwan's cakes.

"It is amazing that she has built such a heritage brand, which are big shoes to fill to take it to the modern century."

Ms Lee, a former lawyer who started her company in 1998, says that her chain uses a proprietary blend of chocolate, with beans imported from South America, Indonesia and Africa.

"Instead of sugar and cream, it is the intensity of the cacao that kicks you at first bite, with a lingering roast-like aftertaste," she says.

She adds that baking techniques have been customised to give the cake a slightly springy texture.

Mr Matthew Chow, 37, founded Matt's The Chocolate Shop in 2012, after being encouraged by friends who have tried his cakes.

"It is a huge market as people can crave chocolate every day," he says.

He sells up to 30 cakes a day.

The self-taught baker compares his cake's rich texture with that of a brownie.

He says: "Each cake is made up of 40 to 50 per cent of dark chocolate with 60 per cent cocoa solids, so it feels like biting into a chocolate bar."

Some shops have been getting creative with chocolate fudge cakes.

Choc.a.bloc in Bedok North has been offering five types of such cakes, including those with banana, pitted cherries and durian, for the past 11 years.

Co-owner Jean Loh, 56, says the fudge is made with five types of dark couverture chocolate from countries such as Belgium and Germany.

She says: "Our custard-like fudge is not too sweet and is flexible enough to go with other sweet ingredients, providing different options to customers."

Despite the alternatives, some still prefer Lana's.

Events manager Goh Xin Ying, 24, who has celebrated all her birthdays with the chocolate fudge cake, says: "My mother and siblings would fight to eat the corners of the cake, which is covered with more fudge. I am concerned that the cake quality may change when the shop changes hands."

Freelance writer Sylvy Soh, 35, a mother of two, says: "Pretty fondant cakes are all the rage for children's birthday parties these days, but they taste awful and are not worth the price.

"I want my kids to appreciate flavour over aesthetics."