Pour marshmallows, butter, peanut butter, honey, and cinnamon into a large microwave safe bowl.
Microwave on high for 45 seconds, remove from microwave and stir.
Repeat until marshmallows have melted. (approximately 1 1/2 minute)
Mix in Honey Comb cereal, covering each piece of cereal well.
Pour mixture into a greased 9x13" pan and refrigerate until set.
Cut into bars and store in refrigerator.