my first attempt was a scoop of semi-melted ice cream plopped onto a cookie with another one squished on top. that didn't really work because the peanut butter cups prevented me from being able to squish everything together evenly.
after some thought i spread some ice cream on a plate and used a round metal measuring cup to cut out a round of ice cream. (i would've used a circular cookie or biscuit cutter if i had one.) then i simply put it on a cookie and then set another one on top.
my only problem with this is the size. you almost have to be snake-like and dislocated your jaw in order to take a bite! i toyed with the idea of making an open faced sandwich but ultimately decided bigger is better.