The millionaire art dealer and his lover have been celebrating her 50th birthday by visiting art museums and dining in lavish restaurants in the country.
TV star Trinny posted a photograph of her and Nigella's ex on her Instagram account having breakfast in Madrid, along with the caption: ''Half a century''.
In another snap, Trinny is seen wearing a new black and white top and posts the message: ''Gorgeous present'', while also sharing photographs of a visit to a gallery and a snap of her daughter Lyla, 10, her child with ex-husband Johnnie Elichaoff.
Trinny started dating Charles, 70, after he split from TV chef Nigella last year. They married in 2003 but divorced seven weeks after photos emerged of him with his hand around her neck.
The break-down of their marriage was played out in public during the trial of their former aides Elisabetta and Francesca Grillo, who were acquitted of fraud in 2013.
Meanwhile, Trinny and Nigella were involved in a war of words online this week, after the fashion expert wrote a blog marking her birthday, seemingly making reference to when Charles put his hand around his ex-wife's neck in a London restaurant.
Trinny wrote: ''It's great that, at 50, life can still grab you by the throat and shake you up.
''And it's even better when you've learned to cope with whatever's thrown at you - so long as it isn't a bedside lamp.''
Nigella appeared to respond to the blog post by writing on Twitter: ''Slut's Spaghetti -- aka pasta alla puttanesca -- is #recipeoftheday. Do I need to say anything more? (sic)''
The brunette beauty attached a photograph of the recipe, before later adding: ''No agenda behind #recipeoftheday! Slut's Spaghetti an old fave of mine. (sic)''
He also slapped a jet-lagged Taylor Hawkins.
The acclaimed performer had just cancelled touring due to a battle with cancer.