Kate Middleton Made It 'Very Clear' What She Wanted for Her Royal Wedding Cake, Says Baker

Kate Middleton had a hand in creating her dream royal wedding cake.

In celebration of the 10th anniversary of Kate and Prince William's nuptials, their royal wedding cake baker Fiona Cairns tells PEOPLE about the "very stressful" task.

"The brief came from Kate, and she was very specific," Cairns recalls in this week's issue. "The theme of the wedding was to be very classical, very imaginative and stylish. Where William and Kate's cake broke with tradition was that she made it very clear she didn't want a cake as tall as some of the previous royal wedding cakes."

The royal bride also requested "softer" icing of sugar paste rather than royal icing and provided a list of 17 flowers and leaves she wanted to be included.

Indigo/Getty Images Kate Middleton

John Stillwell/Getty Fiona Cairns

"It had to be multitiered, and it had to be a fruit cake," Cairns says. "She didn't want any gold or glitter. It wasn't to have any color on it all. It had to reflect the flowers of the four [U.K.] nations, and it also had to reflect the Picture Gallery at Buckingham Palace, where the cake was going to be, to show some of the architectural detail."

"There was a lot to work out!" the baker continues.

Peter Macdiarmid/Getty The Duke and Duchess of Cambridge

The result was an eight-tiered traditional fruitcake adorned with 900 leaf and floral touches and topped with the couple's cipher.

Listen below to the episode of our daily podcast PEOPLE Every Day as we look back at Prince William and Kate Middleton's wedding 10 years later.

The enormous cake lasted beyond the wedding reception — in fact, pieces of the fruitcake were served at all three of William and Kate's children's christenings, most recently for Prince Louis in 2018.

Tune into The CW on Thursday at 8/7c for a tenth wedding anniversary special, People Presents: William & Kate's Royal Anniversary

Cairns and her team were also sworn to secrecy when it came to their project.

"When such a big thing happens, you want to share it with your friends and family, but we couldn't," she tells PEOPLE. "We couldn't tell our children!"

Lewis Whyld/WPA Pool/ Getty; Pascal Le Segretain/Getty

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Cairns recently appeared on ITV's new documentary The Day Will and Kate Got Married to discuss the behind-the-scenes difficulties of getting the three feet-tall fruit cake design into the reception venue — which just happened to be Queen Elizabeth's royal residence in London.

To bring the cake inside to the Picture Gallery in Buckingham Palace, the team had to remove a door. And when the Queen came to visit the team as they were putting the finishing touches on the dessert, she made an unexpected remark about the struggle.

PEOPLE's new special edition, William & Kate: 10 Joyous Years, is now on newsstands and available on Amazon.

"I can remember her saying, 'I hear that you've been dismantling my house,' " Cairns said in the documentary. "And I said to her, 'Well, we had to take a door down from the room below for the trolley to go through with the cake.' But it was all put back so in the end, it was fine."