STEP ONEHEAT oven to 350°F. Coat 13 x 9-inch baking pan with baking spray. Prepare cake mix according to package directions using the water, oil and eggs. Spread evenly in prepared pan. Bake according to package directions. Cool completely in pan on wire rack.
STEP TWOCRUMBLE cooled cake into extra-large bowl. Beat with electric mixer on medium speed until fine crumbs, about 2 minutes. Spoon frosting over cake crumbs. Beat until evenly blended. Cover and freeze 30 minutes.
STEP THREELINE a 15 x 10 x 1-inch baking pan with wax paper. Roll cake mixture into 1 1/2-inch balls. Place on wax paper. Cover and freeze at least 1 hour.
STEP FOURCOMBINE baking chips and shortening in medium microwave-safe bowl. Microwave on HIGH 2 minutes; stir. Microwave at additional 10 second intervals until completely melted and smooth when stirred.
STEP FIVEREMOVE a few cake balls from freezer, keeping the rest frozen. Drop balls into coating mixture. Using a spoon, cover balls with coating, without stirring the balls in coating. Lift each cake ball with fork, allowing excess coating to drip off into bowl. Using toothpick, gently push ball off fork onto wax paper. Immediately sprinkle with decorator sugar. Repeat to coat remaining cake balls. (If coating thickens, microwave at additional 10 second intervals until desired consistency when stirred.) When complete, chill 5 minutes or until coating is set. Serve at room temperature.