Stove
In large saucepan, melt butter over low heat. Add marshmallows and stir until completely melted. Remove from heat. 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
In microwave-safe bowl, heat butter and marshmallows on HIGH for 3 minutes, stirring after 2 minutes. Stir until smooth. Follow steps 2 and 3 above. Microwave cooking times may vary.