I'm not sure if that's available in the UK. But I have tried many different cocoa powders, including some expensive ones, and by far my favorite is Cadbury Bour

I'm not sure if that's available in the UK. But I have tried many different cocoa powders, including some expensive ones, and by far my favorite is Cadbury Bournville. It's lighter colored than most and has a stronger flavor. Maybe it is non-dutched, or at least less so than usual?