What I'm about to say is going to sound a little crazy, but you're going to have to just trust me on this one. When I was a little kid, my uncle took me to an ice cream factory that made the most amazing ice cream sandwiches. There was a rich layer of vanilla ice cream sandwiched between two crisp saltine-style crackers. That's right, salty thin crackers. Before you knock it, you must absolutely give it a try - the salt/sweet combo works well, and the texture is perfect. I personally think they taste best when they're firm, but they're pretty good when the ice cream is gooping out of the sides too.
In order to indulge in this taste sensation, all you have to do is pick up a high-quality ice cream (I suggest vanilla, strawberry, or some sort of vanilla/caramel) and plain saltine crackers.
Choose a rectangular-packed ice cream (this way you can remove the packaging and cut into perfect squares) if possible - else scoop ice cream, place between saltines and use a knife to cut off the excess sides. Place into freezer until slightly-firm and serve!
Alternatively, if you plan on making a lot of sandwiches, you could spread ice cream onto baking sheet, place into freezer until firm and cut into perfect sized squares. No matter which route you choose, remember to have fun! Oh and trust me on this one, it's a delicious combo!