HEAT oven to 350°F. Coat 13 x 9-inch baking pan with no-stick cooking spray. Prepare brownie mix according to package directions using the oil, water and eggs. Bake as directed. Cool completely. Line tray or baking sheet with wax paper.
PLACE frosting in large microwave-safe bowl. Microwave on HIGH 15 seconds; stir until smooth. Trim crisp edges from brownies if necessary. Coarsely crumble brownies over frosting. Mix gently into frosting. Roll into 1-inch balls. Place on prepared tray. Insert lollipop stick into center of each ball. Freeze 30 minutes.
MEASURE chocolate chips and shortening in medium microwave-safe bowl. Microwave on HIGH 1 1/2 minutes; stir. If necessary, microwave in additional 10 second intervals just until melted and smooth.
DIP each frozen brownie pop into melted chocolate, tilting bowl and turning pop to coat completely. Allow excess chocolate to drip off. Immediately roll in chopped nuts, top with decorator sprinkles or drizzle with melted white or peanut butter chips. Place pops in individual foil candy cups on tray. Chill 5 minutes or until chocolate is set. Serve at room temperature.