Place 2 tablespoons vanilla low-fat ice cream in a small microwave-safe bowl. Microwave at high 20 seconds or until ice cream melts. Spread melted ice cream in the bottom of a 9-inch pie plate. Arrange half of crushed chocolate wafer cookies in bottom of pie plate.
Place remaining softened ice cream, 1 cup marshmallows, and 15 crushed candies in a large bowl; beat with a mixer at medium speed until well combined. Spoon half of mixture evenly into crust, and sprinkle evenly with remaining crushed cookies. Spread remaining ice cream mixture over crushed cookies. Arrange whole cookies around outside edge of pie; sprinkle top of pie with remaining 1/4 cup marshmallows and 5 crushed candies. Cover and freeze 4 hours or until firm.