Since when does dessert have to be serious? Ice cream sandwiches in fall flavors are great fun.
Place 12 cookies, flat sides up, on a rimmed baking sheet. Scoop 1/3 cup ice cream into center of each cookie. Place remaining cookies, flat side down, on top of ice cream. Gently press with flattened palm until ice cream spreads to edges of cookies. Freeze until ice cream is semi-firm, about 2 hours. Sandwiches can be frozen on baking sheet until firm, about 4 hours more, and then stored in a freezer bag up to 2 weeks. To serve, transfer cookies to refrigerator until ice cream softens slightly, about 30 minutes.