Nicola Roberts has had "so much fun" working with Cheryl on her new album.
The 32-year-old singer has been helping her former Girls Aloud bandmate write songs for her upcoming fifth solo LP and found it "really exciting" getting back in the studio with her.
Speaking to Closer magazine, she said: "It's honestly been so much fun and it's amazing that we get to work together. Not just being best friends but actually being able to create something together as well - it's really exciting. Cheryl has full control of her record, she's proud of what she's done and I think it really shows in the music."
However, Nicola refused to be drawn on the songs Cheryl, 35, has been recording, despite speculation she's using her lyrics to deal with her break-up from former boyfriend Liam Payne, the father of her 18-month-old son Bear.
She said: "I can't talk about Cheryl's music before she talks about it, I'm sure that when the time is right she will reveal what that means."
The 'Sticks & Stones' singer - who was also joined in Girls Aloud by Sarah Harding, Nadine Coyle and Kimberley Walsh - has also been busy writing music for her own album and can't wait to get the record finished.
Nicola said: "I'm a bit more than halfway through my second record now. I actually only started it last year. I'm really excited about the direction in which it's gone."
While Nicola didn't want to talk about Cheryl's music, it was recently her comeback single 'Love Made Me Do It' is very "edgy" an as well as her split from Liam, she has also drawn reference to her failed marriages to Ashley Cole and Jean-Bernard Fernandez-Versini on the track.