Press the cookie dough onto a round pizza pan, and bake for eight to ten minutes.
Cool cookie dough completely.
Put about half the can of frosting in a bowl and mix in the green food coloring. Divide the other frosting into two bowls. Color each with the purple and orange color.
Spread the green frosting all over the cookie. Put the purple frosting into a plastic bag, cut a corner off, and pipe streaks all over the cookie. Repeat with the orange frosting.
Sprinkle candies and Halloween sprinkles all over the cookie.