1. Line 8-inch square pan with foil, extending foil over edges of pan. Measure peanut butter chips into one medium bowl and chocolate chips into second medium bowl.
2. Combine sugar, marshmallow creme, evaporated milk and butter in heavy 3-quart saucepan. Cook over medium heat, stirring constantly, until mixture boils; boil and stir 5 minutes. Remove from heat; stir in vanilla. Immediately stir one-half hot mixture (1-1/2 cups) into peanut butter chips until chips are completely melted; quickly pour into prepared pan. Stir remaining one-half hot mixture into chocolate chips until chips are completely melted. Quickly spread over top of peanut butter layer.
3. Cool completely. Remove from pan; place on cutting board. Peel off and discard foil; cut into 1-inch squares. Store tightly covered