In large bowl combine KELLOGG'S RICE KRISPIES cereal, butterscotch
In medium saucepan melt butter over low heat. Add marshmallows and peanut butter. Stir until completely melted. Remove from heat. Stir in vanilla. Pour over cereal mixture. Stir until well coated.
Evenly press into 8 x 8 x 2-inch dish coated with cooking spray. Refrigerate for 30 minutes. Cut into squares. Best if served the same day.