With three other investors, the 38-year-old former equity analyst bought the icecream business in November from a couple who had operated it for the past six years.
Dorn, the majority shareholder, does not want to disclose the purchase price but says total revenue exceeds $5 million.
Thirty-two franchisees operate 52 icecream trucks and vans across New Zealand.
"Unfortunately, for the last decade or so, [Mr Whippy's] been a little bit unloved and as a brand it's just been plodding along," he says. "We've come on to give the brand a really good kick in the backside."
Dorn would like to put 30 more vehicles on the road over the next five years. "A lot of the existing franchisees would like a second van."
He says there is also plenty of scope for bringing in new franchisees, with many areas of New Zealand yet to be serviced by the company.
"There's some really exciting growth opportunities for the business on the road. There's probably still 15 franchise areas that don't have Mr Whippy. There's some amazing areas still to be filled."
Dorn says those areas include the Hibiscus Coast, Whangarei, Hutt Valley, Kapiti Coast and Coromandel.
The franchise area for Auckland central - the "jewel in the crown" that includes the all-important Tamaki Drive - is also up for grabs as its owner is planning to move back to Turkey.
An exclusive franchise area costs $35,000 to $50,000, plus about $90,000 for a fully equipped vehicle, he says, and the company does not take a cut of its franchisees' sales.
Instead, the master franchise earns revenue through selling franchisees the products they use, such as the soft-serve icecream.
Dorn will not reveal how much franchisees earn, but says they can make a good living.
Carl Russell, who operates the East Auckland franchise, says he makes 40 per cent of his annual turnover during summer.
During winter, he does runs through industrial areas on weekday afternoons.
"My bread and butter through winter is adults buying Mr Whippy during work time," says 33-year-old Russell. "I couldn't survive without my regular buyers who buy one icecream a week through winter."
He says he enjoys the lifestyle of running a Mr Whippy franchise, which provides plenty of time to spend with his two young sons in the mornings before he hits the road.
Russell has recently traded his old truck for one of the "new generation" Ford Transit Mr Whippy vans.
Dorn says he hopes to lift the profile of the business by phasing out many of the older vehicles.
"One of the things we're doing for the brand is getting rid of those old, crappy trucks and lifting the Mr Whippy brand by putting the new Ford Transits on the road," he says.
"At the end of the day, we're dealing with food and presentation and the brand can only be helped by having the new generation of vans."
But he says some of the "classic-style" trucks will be retained.
"In Blenheim, for instance, the franchisee will always have his Isuzu travelling around. I guess it's in the key metropolitan areas that we'd like to upgrade."
Dorn is also looking at opportunities for exporting Mr Whippy's soft-serve icecream, which is manufactured in Morrinsville by the Tatua Co-operative Dairy Co.
Vietnam and China are potential markets, he says. "The great about thing the [liquid] soft-serve mix is that it's a room temperature product - it doesn't need to be chilled - and it's got a shelf life of about 12 months."
Dorn also wants to grow the business off the road, establishing a chain of Mr Whippy retail stores around the country.
There are already three Mr Whippy kiosks in the St Lukes, Pakuranga and Manukau Westfield shopping centres, but Dorn says those stores do not have any connection with his business.
The company is looking for a coastal site in Auckland to open a flagship Mr Whippy store, to be followed by additional retail stores in other main centres.
"Once we get a flagship retail store running in Auckland it should really lift the company a lot," Dorn says. "It will really put it back on the map."
Mr Whippy
Originally founded in Britain in 1962.
Came to New Zealand in 1964.
52 trucks and vans operated by 32 franchisees.
