Darren McGrady worked with the Royal palaces for 15 years, cooking up delights for the Queen, Prince Philip, and Princess Diana, among others.
And the chef told Recipes Plus that her Majesty generally eats very healthily, but cannot help but crave bitter dark chocolate.
The sugary treat is also a heavy feature in her favourite dessert, a chocolate biscuit cake, according to the chef.
He told the website: “She’ll take a small slice every day until eventually there is only one tiny piece, but you have to send that up.
“She wants to finish the whole of that cake.”
The chef remarked the Queen is very sensible with her food and generally “eats to live”.
She regularly dines on grilled or poached fish and vegetables.
The Monarch also often takes bananas as a snack, neatly chopped into slices.
However, despite her healthy diet, her Majesty can be tempted by Benedicks Bittermints.
The dark chocolate treats with a mint fondant were even handed a Royal warrant by the Queen in 1962.
Mr McGrady said her Majesty was not a “picky eater”, but there are some things she will always refuse.
The Queen likes to eat with the seasons, and will not take anything non-organic.
The chef pointed out she will happily eat strawberries throughout their summer season.
However he warned that the Monarch will reject any fruit that has been genetically modified and is not in season.
He said: “Try including strawberries on the menu in January and she’ll scrub out the line and say don’t dare send me genetically modified strawberries.
“She absolutely does eat seasonal.”