The heir to the throne and his wife had a behind-the scenes tour of Cafe Demel, one of Vienna's treasured coffee houses.
Founded in 1786, the cafe carries the title K&K Hofzuckerbäckerei, a royal warrant dating to the time of the Habsburg Monarchy, which fell at the end of the First World War after ruling Central Europe for 600 years.
Charles, 68, and Camilla, 69, watched pastry chefs demonstrating patisserie skills before sitting down to afternoon tea and a chat with some of the apprentices undergoing training by the firm.
The royal couple watched fascinated as head chef Oliver Csapo and his team showed how they make the cafe's signature apple strudel, Sacher Torte and hand-made tea and cheese biscuits.
Mr Csapo used a copy of The Times newspaper to demonstrate how the team use papers to check that the pastry is thin enough. If they can read the paper through the pastry, they know it is the right consistency.
"I always have a paper handy," the head chef told them.
As the chefs rolled out the mixture and made up the strudel before baking it in the oven for 25 minutes, Camilla, in a navy Fiona Clare coat dress, watched intently. "It looks quite simple but I bet it's very difficult," she said.
Mr Csapo asked her if she liked baking and eating pastries. "I like it. I have a son who does the baking," she said. Her son Tom Parker Bowles is a successful chef.
She and Charles avoided tasting the strudel or having a go at making any of the products themselves but the Prince had a small pastry upstairs when they sat down to a cup of tea and a chat with some apprentices.
Charles told one apprentice how impressed he had been with the kitchen staff. "I was so impressed with the way they poured the chocolate, getting it all absolutely right," he said.
His own previous efforts at something similar were not so successful.
"I did it in Scotland at a bakery last year," he revealed. "It all fell down here," he added, pointing to his trousers and his lap. "They all laughed."
Camilla chatted to Attila Dogudan, whose father, also Attila, is joint owner of the business.
Attila Junior, 33, a business graduate of Royal Holloway University in Surrey, told Camilla he was helping to create a new menu for first and business class customers on British Airways. "Good. That will be very exciting to see it on British Airways," Camilla said.