We already know that Kate does most of the cooking at their Anglesey home, and William claims to make a mean shepherd's pie.
But yesterday they attended a 40-minute workshop at Montreal's top chef school, the Institut de tourisme et d'hotellerie du Quebec.
The Duke and Duchess of Cambridge, dressed in personalised chef's whites, were taught how to make herb and cranberry-crusted lamb, duck confit and lobster soufflé - and William was keen to show that he's a better cook than his host, Quebec Premier Jean Charest.
Mr Charest produced the first lobster soufflé of the lesson, which was brought forward for display with a flourish by Kate. Two minutes later the prince brought his soufflé up, removed the Premier's and said: "Much better! This one is mine."
It was, he said, "a soufflé off."
He then made goats cheese, baby cucumber and elderberry jam and his teacher, Jean-Louis Themistocle said, "This is the best cucumber I have ever seen!"
William also pretended to pinch some strawberries from a bowl and dipped a spoon into a vat of melted chocolate.
"Is there a time limit? Do we eat as we go? I'm quite hungry," he said.
Kate seemed to take it more seriously as she was shown how to make an amuse-bouche of foie gras on a toasted brioche with apple cider jelly.
Student Therese Rindress, 23, who showed Kate the ropes said, "I showed her how to hold the knife and position her hand so that she did not cut herself. She was fantastic. She was very competent with the knife.
"I asked her if she liked to cook at home. She said she likes to cook, but does not do fancy things.
"She makes more big batches, throws a few ingredients together, trying new things. But that's how chefs experiment, throwing things together and seeing if the flavours work."
After the lesson, the Duke and Duchess, accompanied by the Premier and his wife and two of the Prince's senior aides, ate the food they had prepared.
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