"It turned into a massive thing. On Friday nights there used to be cars everywhere on our street with people lined up at our door to pick up orders.
"It started out as a way to earn a little bit of extra money while I was studying but all of a sudden, people were asking about the cupcakes non-stop. I didn't predict it would get this big."
Matheson remembers setting up trestle tables throughout her mother's house one night to hold 4000 cupcakes that had been ordered — that was her mother's breaking point, and the teen realised it was time to take the business to the next level.
She decided to lease a shop at her local shopping centre, but centre management asked her to trial a temporary, pop-up store first as they were concerned the then-19-year-old was too young to handle the responsibilities of a long-term lease.
They shouldn't have been.
There was a "20m line" of eager customers waiting from the moment the store opened — and Matheson had completely sold out within an hour-and-a-half.
She signed a lease almost immediately and today Matheson runs two stores with a third set to open in inner-Melbourne's QV centre this month, and with more pop-up stores to follow.
She's also established partnerships with corporate and wholesale clients including ANZ, Crown Casino, Myer, NAB, Optus and Telstra and has branched into wedding cakes and party favours as well.
And it seems the cupcake business is a lucrative one — Matheson is on track to make A$1.6 million (NZ$1.7m) by the end of 2018, well before her 21st birthday.
She said the degree of her success had been "crazy" — but insists getting rich was never her objective.
"It's absolutely never been my goal and I've never lost sight of my passion on this whole journey," she said.
"I don't wake up thinking about money. People say I must love making lots of money on big days like Father's Day or Mother's Day, but that's not my goal — I love what I do, creating desserts people love, and I never let money get in the way.
"But it's nice to be so young and have the opportunity to make some money and be successful. I never came from a really wealthy family and my family always taught me the importance of genuine hard work."
Matheson said her success had happened so quickly she has had little chance to enjoy it, working around the clock and investing a lot of her revenue back into her company through kitchen supplies and equipment to streamline the business.
And she stressed her phenomenal success has also come with many challenges.
"It definitely hasn't all been smooth sailing. It sounds like it's all rainbows and unicorns but it has come with a lot of hardship. Especially being so young, there are challenges when you start making money — I was investing every single cent into new equipment, with one machine costing A$35,000," she said.
"And it becomes harder the more staff you employ. Next week our 20th staff member will come on board and it is hard to manage so many different people, but I'm learning to be versatile and a strong, independent woman."
She said the secret ingredient to her success has been hard work, quality ingredients and treating staff nicely.
Matheson's signature cupcakes include Rainbow, Salted Caramel, Triple Chocolate and Jam Donut.
