Heat oven to 350°F (if using dark or nonstick pans, heat oven to 325°F). Spray bottom only of 13x9-inch pan with cooking spray.In large bowl, beat cake mix, water, oil, egg whites and 1/8 teaspoon paste icing color with electric mixer on low speed 30 seconds. Beat on medium speed 2 minutes, scraping bowl occasionally. Pour batter into pan. Bake 26 to 31 minutes or until toothpick inserted in center comes out clean. Cool completely, about 1 hour.
Stir remaining 1/8 teaspoon paste icing color into vanilla frosting until well blended. Frost cooled cake with green frosting.
Spoon chocolate frosting into small resealable food-storage plastic bag; seal bag. Cut small hole in one bottom corner of bag. Squeeze bag to pipe frosting onto 2 to 4 inches of one short end of cake to resemble hair around face. (See photo.)
Cut 1 marshmallow in half crosswise; place on cake to for eyes. Shape orange gumdrop for nose. Cut one red gumdrop in half crosswise; place on top of marshmallows for irises of eyes. Use chocolate frosting to add pupils to eyes, and big scar with stitches across forehead and cheek. Flatten remaining gumdrop into mouth; place on cake and add candy corn teeth. Make bolts with chocolate candies.