Gwen Stefani has started work on a new album.

The 44-year-old singer is penning songs for the follow-up to 2006's 'The Sweet Escape' and admits she's been in-and-out of the studio with Pharrell Williams.

She told MTV News US: ''I'm going into the studio tonight with Pharrell, I'm going to be writing and also just seeing what comes along my way. I've been recording a few things...''

Pharrell, who teamed up with Gwen on her 2004 hit 'Hollaback Girl', believes the work the blonde beauty has done so far on her new LP is ''on another level.''

He explained: ''You'll never believe that she does not look her age, she doesn't look like she's had three children -- but that's the cool part, she is her age and she's had three children and she's killing it.

''When I tell you she's killing it, it's another level. Gwen is somewhere else.''

The 41-year-old producer insists people should believe him when he spots something good in another artist because he said the same thing about Miley Cyrus - who shot to fame as the title character in Disney's 'Hannah Montana' - before her stormed into the charts with hits 'We Can't Stop' and 'Wrecking Ball' last year.

He said: ''The last time I said this about Miley everyone was like, 'What? That's Hannah Montana,' and I'm like, 'What? I'm trying to tell you.'

''I mean, only because I've heard it not because I have those ears or I know -- I don't know anything.''