Add the butter to microwave safe bowl and heat for about 1 minute
add in 16 oz bag of marshmallows and heat for 1 - 2 minutes. Check halfway through heating to make sure marshmallows are not overcooking.
add in Rice Krispies and mix thoroughly
Spread the mixture into a greased pan with a greased spatula.
Allow mixture to cool (about 30 minutes), cut into squares and enjoy!