In large saucepan melt butter over low heat. Add marshmallows and stir until completely melted. Remove from heat. Stir in peanut butter until melted.
Add KELLOGG'S® RICE KRISPIES® cereal. Stir until well coated. Using buttered spatula or wax paper evenly press mixture into 13 x 9 x 2-inch pan coated with cooking spray. Cool. Cut into 2-inch squares. Best if served the same day.
MICROWAVE DIRECTIONS: In microwave-safe bowl heat butter and marshmallows on HIGH for 3 minutes, stirring after 2 minutes. Stir until smooth. Add peanut butter, stirring until combined. Follow steps 2 and 3 above. Microwave cooking times may vary.
For best results, use fresh marshmallows. 1 jar (7 oz.) marshmallow creme can be substituted for marshmallows. Diet, reduced calorie or tub margarine is not recommended. Store no more than two days at room temperature in airtight container. To freeze, place in layers separated by wax paper in airtight container. Freeze for up to 6 weeks. Let stand at room temperature for 15 minutes before serving.