By Henry Samuel

These are some of the culinary secrets to emerge from the latest meeting of the select club of chefs who cook for the planet’s most powerful leaders.

The “club des chefs des chefs,” a group of 27 top chefs from the kitchens of the world’s presidents, prime ministers, and monarchs, is gathering in Paris this week to swap recipes and tidbits on dinner-party diplomacy. The cooks insist haute cuisine plays a crucial role in warming ties and sealing international deals.

The club, whose title plays on the double meaning of the French word “chef” for cook and leader, was founded 35 years ago by Gilles Bragard. On Tuesday, he revealed that President Vladimir Putin of Russia maintains the medieval monarchs’ tradition of having everything he eats tried by someone else for fear of poisoning.

“Tasters still exist but only in the Kremlin, where a doctor checks every dish with the chef,” Bragard said ahead of a reception for the chefs hosted by new French president, François Hollande.

Hollande is the sixth Gallic leader to be cooked for by Elysée Palace head chef Bernard Vaussion, who has catered to the gastronomic foibles of French heads of state for the past 40 years. Hollande’s fitness-mad predecessor, Nicolas Sarkozy, a teetotaller and recovering chocoholic, banished cheese from the Elysée, saying it was “too much” for him.

“But François Hollande has brought it back in,” said Bragard, clearly delighted. “Both he and Angela Merkel adore cheese.” London-based Anton Mosimann, a visiting chef to 10 Downing Street who has cooked for several British prime ministers, recounted how Baroness Thatcher once asked for an unusually lavish meal to entertain the then–French president François Mitterrand.

He created an elaborate dish of veal steak with morille mushrooms. During a conversation several years later, Lady Thatcher congratulated him on the meal but added with a frown: “It was very expensive.” “That was Mrs. Thatcher, she never missed a thing,” Mosimann said.

He also recounted how the Duchess of Cambridge recently had a heavy sauce “modified” to make it lighter and that George Bush—he did not specify whether it was the father or son—had two FBI agents taste all his food while on a visit to the U.K.

Attending the gathering from the White House kitchen is Cristeta Comerford, chef to presidents Bill Clinton, George W. Bush, and now Barack Obama. Miss Comerford, who has co-written a cookbook with Michelle Obama to help tackle adolescent obesity, was tight-lipped about the U.S. president’s beetroot aversion, saying the first lady and her husband liked “fruit and vegetables.”

Bragard confirmed that one of Obama’s predecessors, Hillary Clinton, “got rid of the French chef when she arrived at the White House—she found his cuisine too rich.”

He was adamant that the “chefs des chefs” played a vital diplomatic role, pointing out that the great French strategist Talleyrand, credited with the rise of the diplomatic banquet, once told Napoleon Bonaparte: “Give me a good chef and I shall give you good treaties.”

“I often say that if politics divides, then the table brings people together,” he said.

With tensions over the euro-zone crisis still rife, French chefs came up with a masterstroke when Hollande and Merkel met this month to mark 50 years of Franco-German reconciliation; they re-created the famous meal of filet of beef and raspberry macaroons prepared in 1962 for postwar leaders Charles de Gaulle and Konrad Adenauer when they signed their friendship treaty.

The chefs, from Buckingham Palace to China, Sri Lanka and Israel, met in Berlin last week as part of a weeklong annual get-together. They arrived in Paris on Monday for a three-day tour of the French capital.

Beyond their culinary prowess, they have one clear advantage over the leaders they serve, said Mr Bragard: “Presidents come and go, but chefs remain.”