Take ice cream out of the freezer and let it soften a little bit at room temperature, roughly ten to fifteen minutes. As ice cream is softening, take a baking tray or casserole dish and line with parchment paper. Spoon the soft ice cream into the baking tray lined with parchment paper and create one even surface of ice cream that is roughly 1 to 1 1/2 inches thick. Return ice cream to freezer and let ice cream firm up.
Once cookies have cooled (this is very important!) take the sheet of ice cream from the freezer and use a cookie cutter to cut out perfectly round discs of ice cream. Sandwich an ice cream disc between two cookies.
Alternatively, you can just spoon spoonfuls of ice cream between two cookies and skip the freezing and cookie cutter steps. You will have a more "rustic" looking ice cream sandwich. I like the clean lines the cookie cutters create. You can also roll the edges of the ice cream sandwiches in sprinkles or crushed nuts for extra fun.
I recommend assembling the ice cream sandwiches right before you eat them. You can freeze the ice cream sandwiches, but I think the cookies are better (aka softer and chewier) at room temperature.