A bakery studio in Hong Kong is aiming to bounce back from its COVID-19 slump with "illusion cakes" that appear to be everyday objects until you take a slice.

Dear Harley Cake Studio's founders Alison Chan and Cony Lam came up with the idea after baking a custom cake for Chan's nephew, who loves bananas: a thin layer of yellow fondant wrapped around dark chocolate and Italian meringue buttercream.

Posting such creations on social media brought a new wave of customers to their shop, prompting them to switch the focus of their business to special orders and workshops for wannabe cake illusionists.

Now they can make-to-order cakes that look uncannily like almost anything, from a pair of flip-flops to sea-urchin sashimi or even a dish sponge.

"This illusion cake wave is ... kind of saving our business," Chan said.

From a crisis level of three-to-four weekly orders during March and April, the studio is now receiving 15-20 orders a week. An illusion cake costs at least HK$1,500 ($194), with some going for HK$12,000-HK$13,000.

"I’m personally super thrilled that we have reached this stage ... We never expected that this will blow up," Chan said.

"We were just making things that we love, we love baking, we love cake decorating, and we are just making things for fun," she said.

Customer Chase Ko attended one of Dear Harley Cake Studio's private classes to learn how to make custom cakes for her boyfriend's birthday.

"My boyfriend likes Japanese food and Pokemon a lot. Their sushi illusion cake is very cute so I want to design another version with dolls on top of the rice," Ko said.