Melt mars bars and 1/3 cup butter in large pot over low heat. This will take a few minutes of stirring and watching as you don't want the mixture to burn.

Once melted pour in your cereal. Mix well until all combined.

Pour into a 9 x 9 square baking dish.

In a microwaveable bowl add remaining butter and milk chocolate chips. Melt on low stirring every 10 seconds until melted.

Pour melted chocolate over top of rice krispy mixture.

Sprinkle with crushed candy canes and smarties. Let chocolate harden in refrigerator before serving.