Add the 1 ½ butter & marshmallows in a bowl and melt them together. This can be done in the microwave or on the stove top.
add in your food coloring
add in Rice Krispies and mix thoroughly
repeat steps 1 - 3 for remaining colors
Spread the mixture into a greased pan with a greased spatula.
Allow mixture to cool (about 30 minutes), cut into squares
decorate with M&Ms
Serve and enjoy!