CHOP 14 cookies coarsely. Prepare cake batter and bake as directed on package for 2 (9-inch) round layers, stirring chopped cookies into batter before pouring into prepared pans. Cool cakes in pans 10 min.; remove from pans to wire racks. Cool completely.
TINT 1/2 cup frosting with a few drops yellow food coloring; set aside. Spoon 1/2 cup of the remaining frosting into separate bowl. Stir in a few drops each yellow and red food colorings to tint it orange. (Remaining frosting will stay white.)
CUT each cake layer into 8 wedges. Spread with orange, yellow and white frostings to resemble candy corn as shown in photo. Sprinkle each section with matching colored sugars.
CUT remaining cookies into quarters. Attach to rounded edges of cake wedges with remaining frostings.