LINE trays with wax paper.
MICROWAVE morsels in large, uncovered, microwave-safe bowl on MEDIUM-HIGH (70%) power for 1 minute; STIR. The morsels may retain some of their original shape. If necessary, microwave at additional 10- to 15-second intervals, stirring just until morsels are melted. Stir in peanut butter until well blended. Add chow mein noodles and marshmallows; toss until all ingredients are coated. Drop by rounded tablespoon onto prepared trays. Refrigerate until ready to serve.
DOUBLE BOILER METHOD:
PLACE morsels in top of double boiler over hot (not boiling) water. Do not cover. When most of the morsels are shiny, stir just until melted. (Prevent water from coming in contact with morsels.) Remove from heat; stir in peanut butter. Transfer to large bowl. Add chow mein noodles and marshmallows; proceed as above.