Preheat oven to 375°. Line a large sheet pan with a 10-in. sheet of parchment paper. Combine chocolate morsels and butter in a bowl. Microwave on HIGH 40–60 seconds or until mostly melted, stirring after each 20-second interval using a scraper. Add sugar and egg to batter bowl; mix until well-blended. Add flour; mix just until flour is incorporated. Using a scooper, drop 20 level scoops of batter, 1 in. apart, onto pan. Bake 9–11 minutes or until edges are set. (Do not overbake.) Meanwhile, place candy canes into resealable plastic bag; crush using flat side of a meat tenderizer and set aside. Place white chocolate morsels into a microwave safe bowl, and cook uncovered on HIGH 30–60 seconds or until melted, stirring once. Set aside. Remove sheet pan from oven to a cooling rack. Immediately turn over half of the cookies using a spatula; top with peppermint patties and remaining cookies to form 10 sandwiches. Drizzle chocolate over cookies and immediately sprinkle with crushed candies. Transfer to serving platter. Line pan with another sheet of parchment paper and scoop remaining batter onto parchment. Bake 9–10 minutes or until edges are set. Assemble sandwiches as directed above. Makes10–12 cookie sandwiches.