In his new book, Cooking with The Crown, Tom Barker Bowles, son of Queen Camilla, reveals the secrets of the most decadent royal recipes.

But in addition to sharing the Queen Mother's famous cocktail “Gin and Dubonnet” and his mother's simple porridge recipe, Parker Bowles reveals that his mother and stepfather, Prince Charles, have a surprising and passionately shared hobby: they both love to cook.

Apparently, the two enjoy picking mushrooms and “compete deeply about the mushrooms they pick,” writes the food writer.

In a book reported by the Daily Mail, Barker Bowles says that mushrooms are “a kind of obsession” for Prince Charles and Queen Camilla, and that they even try to outdo each other.

According to Barker Bowles, after his mother, the late Queen Elizabeth, passed away at age 96, the king relied on his longtime love of foraging and mushroom hunting.

On the day of his mother's death, then-Prince Charles “spent an hour at Balmoral's bedside and then went to nearby Bark Hall to pick mushrooms alone,” the Daily Beast reported.

On his way home from mushroom picking, he received a phone call informing him that his mother had died and that he was officially King of England.

In his book, Queen Camilla's son also reveals the differences between the two royal families' eating habits and how Prince Charles is dedicated to healthy, clean, farm-to-table meals.

“No one knows more about food and farming than the King, from the rare breeds of sheep and cattle to the traditional varieties of plums, apples, and pears to the best British cheeses,” Bowes writes, describing the King as a “true food hero.”

“The King practices what he preaches,” the cookbook author continues. The King has long preached the importance of sustainable agriculture, and there is no waste at the King's table.”

“Tea, however, wherever it is, is a serious meal, albeit a very relaxed meal,” he reveals in his new book.

“On the other hand, a dinner away from the formal pomp and circumstance is really quite laid-back.”