"They were looking for iconic New Zealand brands with a good track record. They also wanted flavours which worked well with chocolate."
Sommerville sure knows his chilies.
In 2008 he was commissioned to create a handbook about chili peppers called the New Zealand Chili Pepper Handbook.
The Kaitaia Fire Chili Pepper Spice is a hot chocolate that melts in your mouth but will not blow your head off, he said.
"It's a bit of a slow burn. The heat does creep up, though."
He said he had received great feedback so far and people were "loving this chocolate".
The chili guru said Northland's food producers had heaps of potential for similar collaborations.
"If I can be an inspiration for other producers, I'm glad to help out and help push Northland products into the rest of New Zealand. This is a positive news story for the Far North."
Whittaker's said it was a natural step to combine its chocolate with "the finest in local ingredients".
"We also have a lot in common with the artisan producers involved - many are family-owned and operated," said spokeswoman Holly Whittaker.