In large bowl, break up cookie dough. Stir or knead in flour until well blended. Reshape into log. If too soft to cut into slices, refrigerate up to 30 minutes.
Heat oven to 350°F. Line 3 cookie sheets with foil. Cut chilled dough into 16 (1/2-inch) slices. Dip 1 side of each slice in sugar. On each cookie sheet, place 6 slices, sugared side up. Firmly press ring-shaped candies in dough for eyes. Press candy corn in dough for ears, horns, teeth, beak or mouth to create desired creature. (Be sure candies do not extend over edge of dough; they will melt onto cookie sheet.)
Bake 12 to 14 minutes or until edges are light golden brown. Cool completely on cookie sheets, about 25 minutes. Remove cookies from foil.
Meanwhile, divide frosting among small bowls. Add icing color to each; blend until desired color. Place each color frosting in resealable freezer plastic bag; seal bags. Cut small hole in 1 corner of each bag. Decorate cookies as desired by squeezing frosting out through hole in each bag.