Giada De Laurentiis reigns supreme in whipping up a tasty meal fit for a future king and queen!

"Cooking for Prince William and Duchess Kate would probably be the most memorable moment of my career," the Food Network star tells Closer when looking back over her best days. "It was phenomenal."

The chef worked closely with Buckingham Palace to create a special menu for the couple's July 2011 visit to the Santa Barbara Polo & Racquet Club.

"They wanted to eat light and vegetarian," reveals Giada. "I think William wanted to not feel heavy because he had to go play polo afterward!"

kate middleton

Will & Kate at the 2011 event. "It was her first time in California," shares Giada

The results – a Caesar salad and a butternut squash and sweet corn lasagna, which proved to be a royal hit!

"Prince William asked what my secret was," boasts Giada. "He told me that he's been trying to perfect lasagna for years because Kate loves it."

And what did the pair snack on for dessert? "I made cookies and put them in a baggie because William had to go play polo," she says.

The Italian beauty also remembers her time casually chatting with the famous couple after the meal.

"I would never have imagined seeing royals be that easygoing," shares Giada. "William asked about my little girl, and I started to melt."

And the chef adored her refined guests' impeccable manners: "I got a handwritten thank-you note from them, which I have framed!"