Line a large baking sheet with parchment paper or wax paper. Place the Chex cereal, mini pretzels, and salted roasted peanuts in a very large mixing bowl, keeping the M&M’s and sprinkles aside.

Melt the white chocolate, candy melts, or vanilla almond bark in the microwave in 20- to 30-second intervals, stirring well after each interval. Stop heating as soon as the coating is smooth and fluid.

Pour the melted coating over the cereal mixture. Fold gently with a large spatula until most of the cereal, pretzels, and peanuts are lightly covered without crushing the pieces.

Spread the coated mixture in an even layer on the prepared baking sheet. Immediately scatter the red-and-green candies and holiday sprinkles over the top, pressing them lightly into the coating if needed.

Let the snack mix set at room temperature for 20–30 minutes, or refrigerate it for about 10–15 minutes. Once firm, break it into bite-size pieces and transfer it to an airtight container.