Line 1 (15- x 10-inch) jelly-roll pan with parchment paper; grease with butter. Microwave milk chocolate morsels in a large bowl at HIGH 1 to 2 minutes or until melted and smooth, stirring at 45-second intervals. Gently stir in cookie pieces, pretzel sticks, and 3/4 cup coarsely chopped candies. Spread in prepared pan. Sprinkle with 1/2 cup coarsely chopped candies. Let stand until firm (about 6 hours). Break or cut into pieces. Store in a cool place up to 3 days.
Note: We tested with Oreo Double Delight Mint 'N Creme Cookies. Do not freeze bark. Freezing will cause a powdery white coating called bloom.