1. Beat shortening, sugar, egg and vanilla in large bowl until well blended. Stir together flour, cocoa, baking soda and salt; add alternately with milk to sugar mixture, beating until well blended. Cover; refrigerate about 1 hour.
2. Heat oven to 375°F. Drop batter by heaping tablespoons onto ungreased cookie sheet. With palm of hand or bottom of glass, flatten each cookie into 2-3/4 inch circle, about 1/4 inch thick. Bake 8 to 10 minutes or until almost set. Cool 1 minute; remove from cookie sheet to wire rack. Cool completely.
3. Place scoop of ice cream on flat side of 1 cookie; spread evenly with spatula. Top with another cookie, pressing together lightly; repeat with remaining cookies. Roll ice cream edges in chopped baking pieces or candies, if desired. Wrap individually in foil; freeze until firm. About twelve 4-inch ice cream sandwiches.