Brad Pitt
Brad Pitt has cast Ella Purnell in his upcoming Starz series Sweetbitter Juan Medina / Reuters

Brad Pitt, who split with his former wife Angelia Jolie in September 2016, is reportedly "so enchanted" with Ella Purnell that he can't get her out of his mind, In Touch reports.

The report from the website says that the Allied star has been crushing on the British actress, and has cast her in his upcoming Starz series Sweetbitter. Pitt, 53, "is planning on coaching Ella for the show".

Pitt, despite his busy schedule, has been checking in on the 21-year-old actress regularly as she prepares for production of the show. Purnell played the younger version of Jolie in the 2014 movie Maleficent.

"He's so enchanted," a source said. "Brad had Ella in mind from the get-go. He went out of his way to cast her."

Purnell is also said to be "flattered by all the attention she's getting from Brad". She has even told her friends that Pitt has "always been her No. 1 celebrity crush", the source said.

Jolie, who shares six children with Pitt, is reportedly unhappy about Pitt's interest in Purnell, who she thinks is way too young for her former husband as they have a 32-year age gap between them.

"[Angelina]'s furious about Brad's interest in Ella and her being cast in Sweetbitter," the source said. "She absolutely hates that Brad is cavorting with someone who played the teenage version of her in a film.

"[Brad] realises the huge age difference and that everyone would look at the relationship as a midlife crisis mistake," the source said.

However, Brad's attraction to Ella is more than just physical. "He's taken with Ella's spunky, funny demeanour and formidable acting skills.

"It's only a matter of time before Brad takes their relationship to the next level," the source added.