Spraggon said he saw waiters taking a bit of extra care at their table and realised it really was the cooking star.
"We didn't want to disturb her, but I went over and said we were big fans, and she said she'd come to us. I told her about what I did and said if she ever came back I'd love to cook her a hangi."
Spraggon said his Uncle George was "as chuffed as anyone to meet her".
"I think every male is a bit of a fan of Nigella."
Lawson also visited the nearby west coast beaches of Karekare and Piha, sharing photos on social media.
Last week she was on Waiheke, enjoying dinner at Mudbrick Vineyard.
An employee said Lawson watched an idyllic sunset from the patio while enjoying local fish and red wine with a small group of friends.
"She sat outside at a lovely table and watched the sunset with four or five people, but I didn't recognise any of them."
Word had been going around the island that Lawson was there, but there was no fuss when the celeb arrived at the vineyard, she said.
"Sometimes people say, 'Oh, I'm bringing a VIP', but it was nothing like that. It was just like having any other guest, she just came along for dinner and was relaxed."
One fan noted on Lawson's social media pages that she arrived in an Audi S7, which costs about $112,000.
"She didn't come by helicopter or anything," the employee said.
"We always try to just treat everyone like a VIP, and everyone said she was very lovely and pleasant. The waiter said she enjoyed the food."
Lawson also made time to visit Onetangi's Casita Miro for lunch last Thursday. She dined on several sharing dishes with friends including blueskin cockles and smoked kahawai as well as paella and churros at the restaurant which specialises in Mediterranean cuisine.
She was spied by a just-married bride while on Waiheke, who commented on one of Lawson's Instagram posts: "I just saw you at dinner but didn't want to interrupt. My husband and I are here on our honeymoon. I have all your books! Hope the rest of your time in Waiheke is fab!"
Lawson wished her a happy honeymoon in response.
The cook's social media was also rife with invitations from Kiwis to pop in for home-smoked mussels and cuppas.
Whittaker's marketing manager Jasmine Currie said they were excited to be "working on something very special" with Lawson.
"We are proud to work with such a passionate Whittaker's chocolate lover and she is a great ambassador for our brand. We can't wait to share what we've been working on – watch this space!"
In February, Lawson made a whirlwind trip here to promote her new book, At My Table, and to host An Evening with Nigella Lawson sessions in Auckland and Christchurch.
