Preheat oven to 350°. Spray 13 x 9-inch baking dish with cooking spray; line rimmed baking pan with parchment paper. In large bowl, stir cake mix, egg whites, oil, pumpkin pie spice and 1 cup water; spread in prepared dish. Bake cake 28 minutes or until toothpick inserted in center comes out clean; cool completely in pan on wire rack.
Break up cake into smaller pieces. In food processor, in 2 batches, pulse cake pieces until it resembles small crumbs; transfer to large bowl. With hands, work in frosting until mixture sticks together; roll into 1 1/2-inch balls and place on prepared pan.
Melt candy coating as label directs. Dip 1 end of cake pop sticks into candy coating, then insert into center of cake balls; freeze 20 minutes.
Dip cake balls into candy coating to completely cover, allowing excess to drip off; sprinkle with nonpareils and place back on pan. Refrigerate cake pops 10 minutes or until hardened. Makes 23 cake pops.