Line tray with wax paper. In medium microwave-safe bowl, place butterscotch chips, peanut butter chips and shortening. Microwave at HIGH (100%) 1 minute; stir. If necessary, microwave at HIGH an additional 15 seconds at a time, stirring after each heating, just until chips are melted and mixture is smooth when stirred. Immediately add chow mein noodles; stir to coat. Drop mixture by heaping teaspoonfuls onto prepared tray or into paper candy cups; let stand until firm. If necessary, cover and refrigerate until firm. Store in tightly covered container in refrigerator. About 2 dozen candies.