Line two large rimmed baking sheets with parchment paper or wax paper and set aside.
In an extra-large mixing bowl, combine the Rice Chex, Corn Chex, gluten-free pretzels, and roasted peanuts. Gently toss to distribute the ingredients evenly.
Place the white chocolate chips or chopped almond bark in a medium microwave-safe glass bowl.
Microwave the white chocolate on 50% power in 30-second intervals, stirring thoroughly between each interval until the chocolate is completely smooth and melted. Do not overheat, as white chocolate seizes easily.
Immediately pour the melted white chocolate over the cereal mixture. Use a large silicone spatula to gently fold the mixture until every piece is evenly coated with chocolate.
Quickly fold in half of the holiday M&Ms while the chocolate is still wet.
Spread the mixture out in a single, even layer across the prepared baking sheets.
While the chocolate is still tacky, sprinkle the remaining M&Ms and holiday sprinkles over the top.
Allow the mix to sit at room temperature for approximately 30-60 minutes, or place in the refrigerator for 15 minutes, until the chocolate coating is completely firm.
Gently break the hardened mix into clusters and store in an airtight container at room temperature.