Now she leaves her "Healthy Food Guide hat" at home to chat about the perfect mash.
The very best super-creamy mashed potato like you get in a good restaurant involves what food writer Jeffrey Steingarten calls "an escapade in animal fat", Niki says.
This recipe has a ratio of around 2-to-1 potato to butter (so it's effectively one-third butter).
Niki tried making it at home.
"It was really hard for me to put all that butter in there, but it does make the most incredible mashed potato ... It does give you the mashed potato that is like the restaurant potato."
Here are her tips for everyday mashed potato:
Use a floury potato (if they're in a packet it might say they're for spuds or mashing) They can get gummy or watery if you use a waxy one.
Her favourite is Agria.
To make a super creamy, lump-free. mash you can also use a potato ricer – which resembles an overgrown garlic crusher, Niki says.
Auckland chef Damian Husted recommends baking potatoes in advance, scooping out the flesh out then mashing or rice-ing that.
That will keep your mash dry and fluffy, Niki says.
Melted butter should always go in cold.
You can really add whatever you like – garlic, blue cheese, mustard, fetta, wasabi...
If you have some mash leftover, why not try making Gluten-Free Lemon Cake using Mashed Potatoes.
And if you're a potato superfan, find out about their fascinating history.