First, line a large baking sheet with parchment paper to minimize mess. Since this won't be going into the oven, you can certainly substitute wax paper.
Measure out the Chex cereal, Cheerios, and pretzel twists, and place into a large Ziploc bag.
2 cups Chex Mix, 1 cup Cheerios , ½ cup pretzel twists
Place the white chocolate into a microwave safe bowl and follow the instructions on the label regarding melting. It's usually about 15 seconds on high, stir, return and repeat until you have beautifully melted chocolate. I have found that different brands have different instructions, so, to ensure the best outcome, read the label.
6 ounces white chocolate
Pour the chocolate over the cereal mixture in the bag, seal, and shake it up in the bag.
Add the M&M's and holiday sprinkles to the bag and give it a few more gentle shakes.
½ cup M&Ms, 4 tablespoon sprinkles
Pour the mixture out onto the cookie sheet spreading evenly.
Place in the refrigerator for about 60 minutes. Remove and break into pieces. Serve!