Queen's 90th birthday: What it's like baking Her Majesty's birthday cake
"I just thought it was a sick joke. I was like, 'Why are you lying? Why would she want me to make her cake?'" Nadiya Hussain told Newsbeat.
The Great British Bake Off winner was asked by Buckingham Palace to make a cake for Her Majesty's 90th birthday.
And since that invitation she's been in her kitchen at home working on it, before proudly showing it to her majesty at Windsor Castle.
"She asked me what I've got inside the cake," she remembers.
"I said 'orange drizzle', and she said 'Does it cut?'.
"So I figured she had a fear it wouldn't cut, or she's had a previous experience when it didn't cut.
"And it cut and it went right the way through. I said 'Yes it cuts'. I was worried that it wouldn't and it did."
As the Queen met thousands of onlookers, royal gun salutes were fired from each of the UK's capital cities.
"I mean how often am I going to get to do this? I tried to enjoy every single moment."
But Nadiya remembers preparations being a trifle difficult at times.
"The design completely came off the cuff. I've gone for a vibrant colour and I've gone for the complete opposite of a traditional cake," she told Newsbeat.
"I'd love to say that somebody gave me a specification but I had nothing which made it even harder.
"It was literally a free for all. I had complete creative control."
At one point Nadiya had eight cake designs in front of her but she eventually decided on an orange drizzle cake filled with vanilla butter cream and orange marmalade.
She says she tried to act as though she was making a cake for someone else.
"It's really odd because it hasn't quite dawned on me who exactly I'm making the cake for," she says.
"I've been making a cake, making the kids dinner and making packed lunches."
Nadiya also didn't drive the cake from her house to Windsor Castle.
She had a courier for that.
"The one thing that stresses me out the most is travelling with the cake in the car."
Already Nadiya knows she's going to get some criticism for her design but laughs: "I'm an amateur baker."
But she says "nothing can be scarier than Paul Hollywood's scowling face, right?"
Find us on Instagram at BBCNewsbeat and follow us on Snapchat, search for bbc_newsbeat