Melt butter in a saucepan on medium heat
Add marshmallows and vanilla and stir until melted
Turn heat off
In a large bowl add rice Krispy and pour the marshmallow-butter mixture and mix together using a spatula
Prepare a baking dish using non-stick spray or parchment paper on the bottom
Add mixture to the pan
Add the holiday M & Ms
Refrigerate for 40 minutes