He decided to see if he could make desserts that the couple could enjoy, using only plant-based ingredients, but it was harder than he imagined. “It was a lot of research and trial and error – a lot of error,” Deh says with a chuckle.

Now the chef, who left Rosewood Hong Kong at the end of August, is launching his Essentia by Holger Deh line of plant-based pastries, cakes and chocolates. He will open a three-month pop-up at Pacific Place on Hong Kong Island starting on December 2.

The raspberry tart has a flaky pastry that doesn’t fall apart when slicing it, the refreshing mango creme has a centre of coconut confit, but what will probably be his bestseller is the giant Ferrero Rocher-like plain chocolate and hazelnut treat. Deh’s creation is filled with a healthier version of Nutella, with less sugar and no skimmed milk powder, butter or whey.

After accepting the challenge, Deh spent his weekends and days off from Rosewood experimenting with plant-based ingredients such as non-dairy butters and creams.

“When I was trying plant-based butter, it took three months to get it right,” he explains. “The pastry would rise nicely but then would collapse.” Now, though, he has found one from the UK that works well for baking.

Deh also tried many plant-based creams, but found them too sweet. “You would think they would be more healthy, but they have more sugar in them. I think maybe they are trying to mask the original taste,” he says.

The chef, who has worked in hotels in the United States, Spain, Jordan, Malaysia and Macau for more than 22 years, was also interested in reducing the amount of sugar in his desserts, preferring to use brown sugar instead of sugar replacements that he doesn’t think are that healthy.

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“I lost 10kg [22 pounds] in the last three months, because of having a healthier lifestyle,” Deh says. “At the hotel, I had to taste all the time, which makes a big difference. That’s a lot of sugar intake.”

While months of research sparked Deh’s interest in trying new plant-based products to use in his line of pastries, it hasn’t inspired him to become vegetarian or vegan – but he has made a switch from cow’s milk to oat milk in his coffee.

Deh was frustrated many times during his experimentation. “You think ‘this cannot be so difficult’, but it was really difficult in the beginning, and I’m still learning every day. I’m always on the hunt for what I can do better, what I can replace.”

One of his early disappointments was making eclairs and choux pastry, which have so far fallen flat. “It was painful,” he says, but he hasn’t given up. He savours each little breakthrough, which motivates him to keep going.

“I played football as a kid, and you want to win, [though now] it’s not about winning. If I have something in my mind, I try to accomplish it as much as I can. I don’t want to say [I’m] stubborn, but that comes very close.”

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Deh plans to have more pop-ups before opening a more permanent, physical store, if the market is interested and he can find the right location. An online shop is already in the works.

For the Pacific Place pop-up, he will sell five pastries at around HK$60 [US$7.70] each, cakes priced from HK$480 to HK$550, and individual chocolates and sable cookies (prices to be determined).

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“I never thought I would do this. It’s something that’s interesting, something different. I’ve been working in five-star hotels for 22 years and going out on your own, of course it’s scary,” Deh says. “You have sleepless nights, many things to coordinate, but I think it will be worth it.”