Ideal for catered holiday parties, REESE'S PIECES Double Chocolate Bark is easy to make in big batches. Delight guests with bites of classic candies they love: REESE'S PIECES Minis and chopped HERSHEY'S Milk Chocolate Bars.
Lightly spray one 18x26-inch full sheet pan with vegetable cooking spray. Place parchment paper on prepared pan. Sprinkle 8 oz. REESE'S PIECES Minis evenly onto bottom of prepared pan. Set aside.
Place HERSHEY'S Milk Chocolate Chips and shortening in large microwave-safe bowl. Microwave at MEDIUM (50%) 2 minutes; stir. If necessary, microwave an additional 15 seconds at a time, stirring after each heating until chips are melted, and mixture is smooth when stirred.
Pour melted chocolate over REESE'S PIECES Minis in prepared pan, spreading with an offset spatula, if needed, to approximately 1/2-inch thickness. Immediately top with remaining REESE'S PIECES Minis and Chopped HERSHEY'S Milk Chocolate Bars, lightly pressing each into melted chocolate.
Refrigerate 30 minutes or until firm. Break into pieces. Store in tightly covered container in cool, dry place.