The British singer drove from her home in London to Wales over the recent Easter holiday break to spend three days working with songwriter Amy Wadge at her recording studio.
Wadge's studio is based in a shed in her backyard, and Halliwell reveals the experience was unique.
In a post on her blog, Halliwell writes, "On Bank Holiday Monday I drove to Wales... I had a writing session with a lady I had never met before. I knew she was talented (she had written with Ed Sheeran) and now she wanted to write with me, cool... I drove through the rolling hills of Wales to a 'ginger bread' house, and was welcomed by a sparkling woman... Her house was cosy, full of love and memories. We then went to the back garden to her 'magic shed' (this is where she wrote with Ed Sheeran)... We had the most magical time... We wrote the most authentic songs only two women could write together...
"I'm smiling gratefully from my week in Wales with Amy, in the magic shed."