"The ceremony started at sunset and they got married inside the house.
"When the ceremony was over, guests cheered.
"The reception was in a white tent in the backyard.
"Her sister Haylie was very involved in the wedding prep too. Hilary and Haylie are very close," the insider spilled.
Hilary posted the first snap from her big day to her Instagram on Monday.
In the photo, the newlyweds could be seen standing by a vintage car with "just married" written on its back windscreen.
Hilary wore a chic white gown, with her hair swept back in a headband and carried a small posy of pink roses.
Matthew looked handsome in a chic black dinner suit.
Other photos of the event are yet to surface, however Hilary's longtime stylist and friend Jessica Paster hinted at the wedding's vibe with a flowery Instagram captioned, "Winter solstice ... a day of luv ❤️🌺☃️🦋"
The couple announced their engagement in May, with Hilary posting a sweet snap of her smiling and showing off a huge diamond ring.
"He asked me to be his wife♥️" she captioned the loved-up pic.