Grab a 13x9 baking pan and coat the bottom and sides with butter or cooking spray.
MELT the butter over medium-low heat. Once completely melted, add the marshmallows into the pot. Stir continuously until they are almost completely melted. You may add the white chocolate at this point. Continue to stir until everything is melted and combined.
Mix in the Rice Krispies one cup at a time. You will add between 5-6 cups depending on how dense you like them.
Transfer the mixture into your greased pan. Spread them out evenly.
Garnish the top with M&Ms. You could even cut them out with egg shaped cookie cutters if you wanted to take them a step further.