Microwave chocolate chips for approximately 1 minute untill completely melted. Add peanut butter and rice krispies . When mixture is cool, but not cold, add marshmellows. Return to microwave and heat for 30 seconds. Mix gently so that the marshmallows begin to melt and stick together slightly.DO NOT over heat. Mixture should be slightly sticky and chunky. Spread into a 9x13 pan and put into freezer to cool quickly. Cut into squares and serve chilled.