• Line 9-inch square baking pan with parchment paper, allowing excess paper to hang over the sides. This will help in unmolding the marshmallow cereal treats. Set aside.
• In a large sauce pot, melt butter over medium heat. Add marshmallows and salt. Stir to combine until marshmallows are melted and smooth. Remove from heat.
• Add in cereal. Gently fold to combine until melted marshmallow mixture has been evenly distributed. Stir in peppermint candy. Fold until distributed.
• Transfer 1/3 of cereal mixture to prepared baking pan. Press into an even layer. Sprinkle 1/2 of dark chocolate chunks. Top with another 1/3 of cereal mixture. Press into an even layer. Sprinkle remaining 1/2 of dark chocolate chunks. Finish with remaining 1/3 of cereal mixture. Press into an even layer. Use additional sheet of parchment paper to help ensure mixture is level on top.
• Cool mixture to room temperature.

Topping:

• Gently melt white chocolate over a bain-marie until smooth. Alternatively, heat white chocolate chips in the microwave according to package instructions.
• Spread melted white chocolate over marshmallow cereal treats. Allow chocolate to set.
• Gently melt dark chocolate over bain-marie until smooth. Alternatively, heat in a microwave safe bowl at half power in 15-20 second intervals until smooth and melted.
• Spread melted dark chocolate over set white chocolate. Immediately sprinkle peppermint candy on top. Allow chocolate to set.
• Unmold marshmallow cereal treat from pan by lifting from excess parchment paper. Place on a cutting board. Slice in 9 equal squares, or desired serving sizes.