"It's crazy to think what's possible just from a hole in the wall," Christian says as we sit in the lounge room of the family home on Sydney Road in Brunswick, a bohemian shopping strip a stone's throw from the Melbourne CBD.
The conversation is interrupted from time to time as customers appear at the window for coffee.
Then more customers come. They just keep coming.
Outside, on the nature strip, people sit at small tables sipping coffees and eating cakes. There are normal, family homes on either side.
It's a juxtaposition that takes some getting used to, reports news.com.au.
For more than a year, Christian, 26, his two sisters Francesca, 24, and Paris, 28, have been operating one of Melbourne's most unique businesses from their lounge room window.
Mum Julie works tirelessly behind the scenes, too.
"It kind of started as a bit of a joke from Dad," Paris says. "He said to Mum we should sell coffee and cake out of the window."
That was 15 years ago when the kids were trotting off to primary school.
"He was always saying it as a joke, that we should sell to our friends' parents on the way to school," Christian says. "Obviously, Mum brushed it off."
Years later, that seed of an idea was presented to Julie again.
"For me, it was just an absolute no at the start," she says. "But when Christian raised the idea later, it was a different time and it was a different home."
"Everything kind of fell into place," Paris says.
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The kids have all moved out now, but there was a period when they all lived and worked together under the same roof six days a week.
Francesca bakes the treats for the window, including salted chocolate chip cookies that she says are the favourite among customers. Christian does the financials and Paris does social media. Then they all share roles.
Success has come quickly, Christian says.
"I have been surprised by how well it's done. I set a goal when we started. Like, if we could make X amount of dollars on a daily basis then that would be good. And now we've gone above and beyond that."
For a long time, just a black curtain separated the makeshift coffee shop from the rest of the family home.
They now have a proper wall in place, but the sound of the coffee machine and the conversations between customers and their barista travel through the house. And almost everyone who appears at the window is a regular.
"We all said from the start that we have to know people's names," Paris says.
"So on Saturdays when all of our regulars come, it's like talking to friends. It's like, 'Hey Jack, hey Steph, hey Sophie'. We know everybody that comes to our cafe now."
"We've had loyal customers from day one," Julie says. "And friendships that have formed out it, not just in the window."
The best part, she says, is working with her kids from home.
"I look at it like it's a privilege, seriously. That's not to say we don't have our ups and downs but it's normal. And we're able to learn things and deal with issues gently, amongst ourselves."