Heat oven to 350°F. Bake cookies as directed on roll. Cool completely, about 20 minutes.
For each sandwich cookie, spread frosting on bottom of 1 cookie. Arrange 8 licorice pieces on frosting to look like spider legs. Top with second cookie; press together gently.
Using frosting, attach 2 baking bits to top of each cookie to look like eyes. Place dot of decorating gel in center of each eye.