How to clone bootcamp partition on Mac?

Hello!

I currently have a 200GB bootcamp partition on my 2TB internal iMac hard drive. I want more space for my windows partition. I have a spare 500GB Hard drive laying around, and was wondering if there was a way that I could clone the bootcamp partition from my iMac onto that drive. I'd still want it to be bootable.That way I could have an extra 300GB of space without sacrificing my internal HD. Is there an easy way to do this? Thanks!

Thomas