haha! Yep, blender. That probably would have been good for me to mention :P I use about 1/2 water, 1/2 ice and the pb, blend up, and it tastes just like a horribly decadent milk shake. I'm obsessed with it at the moment.
I haven't tried the cream cheese yet, I'm thinking I might use that trick to help me get through some banana flavored shakes I've been trying to forget I still have.