Well I think Poppin Pastels is what this technique is called.
I have to admit that my Stampin' Pastels don't see the light of day very often. It's not that I don't like them, more a case that I don't really know how to use them but I'm chuffed with how this one turned out. It's not even the neatest of cards - could of done with better measuring but at the time I was just 'playing'.
I think these hidden gems will be making a bit more of an appearance in future.